担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00248-023-02341-4

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3389/fmicb.2023.1298681

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3389/fmicb.2023.1230548

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.rsma.2023.102984

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2965/jwet.22-095

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：{MDPI} {AG}  

DOI： 10.3390/w14071018

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jgar.2022.04.024

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.ME22038

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Society for Microbiology  

Here, we report the draft genome sequences of putative aerobic anoxygenic phototrophic bacterial strains
<italic>Jannaschia</italic>
sp. AI_61 and AI_62, isolated from seawater around a coastal aquaculture in Ainan, Ehime, Japan. These genome sequences could be useful for our understanding of the variation of aerobic anoxygenic phototrophs in the genus.

DOI： 10.1128/MRA.00491-21

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

Water systems in Southeast Asia accumulate antibiotics and antibiotic resistance genes (ARGs) from multiple origins, notably including human clinics and animal farms. To ascertain the fate of antibiotics and ARGs in natural water environments, we monitored the concentrations of these items in Thailand. Here, we show high concentrations of tetracyclines (72,156.9 ng/L) and lincomycin (23,968.0 ng/L) in pig farms, followed by nalidixic acid in city canals. The city canals and rivers contained diverse distributions of antibiotics and ARGs. Assessments of targeted ARGs, including sul1, sul2, sul3, and tet(M), showed that freshwater (pig farm wastewater, rivers, and canals) consistently contained these ARGs, but these genes were less abundant in seawater. Although sulfonamides were low concentrations (<170 ng/mL), sul1 and sul2 genes were abundant in freshwater (minimum 4.4 x 10(-3) -maximum 1.0 x 10(0) copies/16S), suggesting that sul genes have disseminated over a long period, despite cessation of use of this class of antibiotics. Ubiquitous distribution of sul genes in freshwater appeared to be independent of selection pressure. In contrast, water of the coastal sea in the monitored area was not contaminated by these antibiotics or ARGs. The density of Enterobacteriales was lower in seawater than in freshwater, suggesting that the number of ARG-possessing Enterobacteriales falls after entering seawater. From the pig farms, through rivers/canals, to the coastal sea, the occurrence of tetracyclines and tet(M) exhibited some correlation, although not a strong one. However, no correlations were found between concentrations of total antibiotics and ARGs, nor between sulfonamides and sul genes. This is the first comprehensive study showing Thai features of antibiotics and ARGs contaminations. The pig farm is hot spot of antibiotics and ARGs, and sul genes ubiquitously distribute in freshwater environments, which become less abundant in seawater. (C) 2021 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.scitotenv.2021.148423

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Informa UK Limited  

Background and Objectives: One major source of antibiotic contamination in the sea is from aquaculture. We monitored the concentration of commonly used antibiotic classes and antibiotic resistance genes (tet(M), sul1, sul2 and sul3) in aquaculture farms in Peninsular Malaysia. Methods: Antibiotic residues and resistance genes were quantified using high-performance liquid chromatography and real-time PCR respectively. Risk quotients in European technical guidance document on risk assessment was used to assess the potential environmental risk. Results: We detected 23 antibiotics with tetracyclines, sulfonamides and quinolones were the most frequently detected classes, indicating a wide distribution of antibiotics in Malaysian aquaculture farms. The dendrogram and heatmap revealed three groups of antibiotic concentration patterns but with no differences in the types of antibiotics usage among aquaculture farms. The ARGs (10(-3) copies/16S) were detected in >90% of the sites except for sul3. Ciprofloxacin, enrofloxacin, norfloxacin and lincomycin posed risks to cyanobacteria and algae in Kelantan, Perak and Pahang. Conclusion: Relative to Asian aquaculture farms, the residues detected here were at low or moderate levels except for quinolones. This study will be useful to develop effective management of aquaculture wastewater in order to mitigate antibiotic pollution and transmission of ARGs to humans through the food chain.

DOI： 10.1080/20964129.2021.1926337

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.etap.2020.103557

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microbiology Research Foundation  

Most animals cannot digest cellulose but have symbiotic microbes that degrade the matrix polysaccharides of plant matter. Herbivorous and omnivorous marine fish are similarly expected to rely on symbiotic microbes, but reports to date on cellulase-producing bacteria in fish intestines are limited. Here, we report the isolation of new cellulase-producing bacteria from the marine omnivorous teleost, blackfish (Girella melanichthys), and the characterization of cellulase activity. Three strains of cellulase-producing bacteria sp. were isolated from the hindgut of wild G. melanichthys. The strains of cellulase-producing bacteria grew in medium with artificial seawater but not in NaCl alone. Growth was optimum at 20-35°C, but there was no growth at 40°C, suggesting adaptation in a marine environment at a low temperature. Isolates were identified to Microbulbifer sp., among which GL-2 strain produced a high enzyme activity. The GL-2 strain was further used for enzyme characterization with carboxymethyl cellulose (CMC) as the substrate. Maximum activity of the cellulase was observed at 60°C, and activity was more than 30% at 20°C, while commercial cellulase Enthiron showed an optimum activity at 50°C and 17% activity at 20°C. Hydrolytic products by GL-2 cellulase were cellobiose but not glucose, suggesting a deficiency of β-glucosidase activity. Active gel electrophoresis containing CMC showed five bands, suggesting several cellulolytic enzymes. The GL-2 strain and its enzyme are potential probiotics for aquaculture fish and the industrial production of cellobiose.

DOI： 10.2323/jgam.2020.05.001

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Microbial Ecology  

DOI： 10.1264/jsme2.me20150

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Informa {UK} Limited  

DOI： 10.1080/10643389.2019.1692611

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Society for Microbiology  

<title>ABSTRACT</title>
<italic>Microbulbifer</italic> sp. strain GL-2 was isolated from the intestine of a teleost, <italic>Girella melanichthys.</italic> Here, we report the complete genome sequence of this strain, which produces cellulase(s). Twelve cellulase candidate genes were found on the chromosome.

DOI： 10.1128/MRA.00746-20

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media SA  

Marine aquaculture fish and the environment are possible hot spots for the maintenance and spread of antibiotic resistance genes (ARGs). We here show the time courses of changes of six tetracycline resistance genes (tet) in fish rearing seawater and fish intestine in tank experiments. Experimental tanks were prepared as oxytetracycline (OTC) administration tanks and those without OTC. It was found that tet(B), tet(M), and tet(W) were dominant in seawater among the six tet genes. tet(B) and tet(M) abundances increased immediately after OTC administration, indicating that OTC served as a selective pressure to increase the proportion of tet-possessing bacteria. In contrast, the abundance of tet genes in the fish intestine did not differ between the with- and without-OTC administration groups, and clearly was not altered by OTC administration. Profile changing of tet in seawater and fish intestine did not synchronize. These observations suggested that the dynamics of intestinal tet-possessing bacteria do not directly reflect the environment, but reflect selection within the intestine.

DOI： 10.3389/fmicb.2020.01764

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>ABSTRACT</title>Biofilms in water environments are thought to be hot spots for horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs). ARGs can be spread via HGT, though mechanisms are known and have been shown to depend on the environment, bacterial communities and mobile genetic elements. Classically, HGT mechanisms include conjugation, transformation and transduction; more recently, membrane vesicles (MVs) have been reported as DNA reservoirs implicated in interspecies HGT. Here, we review the current knowledge on the HGT mechanisms with a focus on the role of MVs and the methodological innovations in the HGT research.

DOI： 10.1093/femsec/fiaa031

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その他リンク： http://academic.oup.com/femsec/article-pdf/96/5/fiaa031/33144680/fiaa031.pdf

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Plankton Society of Japan/The Japanese Association of Benthology  

DOI： 10.3800/pbr.14.276

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.scitotenv.2019.06.304

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

© 2019 Elsevier B.V. The use of antibiotics in aquaculture causes selection pressure for antibiotic-resistant bacteria (ARB). Antibiotic resistance genes (ARGs) may persist in ARB and the environment for long time even after stopping drug administration. Here we show monthly differences in the occurrences of genes conferring resistance to sulfonamides (i.e. sul1, sul2, sul3), and tetracyclines (tet(M)) in Japanese aquaculture seawater accompanied by records of drug administration. sul2 was found to persist throughout the year, whereas the occurrences of sul1, sul3, and tet(M) changed month-to-month. sul3 and tet(M) were detected in natural bacterial assemblages in May and July, but not in colony-forming bacteria, thus suggesting that the sul3 was harbored by the non-culturable fraction of the bacterial community. Comparison of results from Taiwanese, Japanese, and Finnish aquaculture waters reveals that the profile of sul genes and tet(M) in Taiwan resembles that in Japan, but is distinct from that in Finland. To our knowledge, this work represents the first report to use the same method to compare the dynamics of sul genes and tet(M) in aquaculture seawater in different countries.

DOI： 10.1016/j.scitotenv.2019.03.111

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1002/mbo3.710

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/mbo3.710

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Microbial Ecology  

DOI： 10.1264/jsme2.me19099

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

添付ファイル： Reprint Text1-s2.0-S0048969718310660-main.pdf

DOI： 10.1016/j.scitotenv.2018.03.305

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1128/genomeA.00297-18

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1371/journal.pone.0198613

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media S.A.  

Microbial extracellular hydrolytic enzymes that degrade organic matter in aquatic ecosystems play key roles in the biogeochemical carbon cycle. To provide linkages between hydrolytic enzyme activities and genomic or metabolomic studies in aquatic environments, reliable measurements are required for many samples at one time. Extracellular proteases are one of the most important classes of enzymes in aquatic microbial ecosystems, and protease activities in seawater are commonly measured using fluorogenic model substrates. Here, we examined several concerns for measurements of extracellular protease activities (aminopeptidases, and trypsin-type, and chymotrypsin-type activities) in seawater. Using a fluorometric microplate reader with low protein binding, 96-well microplates produced reliable enzymatic activity readings, while use of regular polystyrene microplates produced readings that showed significant underestimation, especially for trypsin-type proteases. From the results of kinetic experiments, this underestimation was thought to be attributable to the adsorption of both enzymes and substrates onto the microplate. We also examined solvent type and concentration in the working solution of oligopeptide-analog fluorogenic substrates using dimethyl sulfoxide (DMSO) and 2-methoxyethanol (MTXE). The results showed that both 2% (final concentration of solvent in the mixture of seawater sample and substrate working solution) DMSO and 2% MTXE provide similarly reliable data for most of the tested substrates, except for some substrates which did not dissolve completely in these assay conditions. Sample containers are also important to maintain the level of enzyme activity in natural seawater samples. In a small polypropylene containers (e.g., standard 50-mL centrifugal tube), protease activities in seawater sample rapidly decreased, and it caused underestimation of natural activities, especially for trypsin-type and chymotrypsin-type proteases. In conclusion, the materials and method for measurements should be carefully selected in order to accurately determine the activities of microbial extracellular hydrolytic enzymes in aquatic ecosystems
especially, low protein binding materials should be chosen to use at overall processes of the measurement.

DOI： 10.3389/fmicb.2017.01952

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

Background The novel tandem genes mef(C) and mph(G) have been reported in marine bacteria in Japan. This paper aimed to characterise the extent of environmental distribution of mef(C) and mph(G) as well as their dissemination and persistence in aquatic bacterial communities. Methods Erythromycin-resistant bacteria were isolated from Japan, Taiwan and Thailand aquaculture sites. The mef(C)–mph(G) genes were detected by PCR. The size of mobile genetic elements conveying mef(C) and mph(G) was examined by Southern blotting. The conjugation rate was assessed by filter mating. Results The mef(C)–mph(G) tandem genes were distributed in erythromycin-resistant isolates from aquaculture seawater in Japan and northern Taiwan and in animal farm wastewater in Thailand. A total of 29 bacterial isolates were positive for mef(C)–mph(G). The genes were found on vectors of various sizes. Partial sequencing of the traI relaxase gene revealed homology with a pAQU1-like plasmid, an IncA/C-type plasmid and an SXT/R391 family integrative conjugative element (SRI) as vectors. Thirteen isolates (45%) were positive for traI(pAQU-IncA/C-SRI), whereas the others were negative. The traI(pAQU-IncA/C-SRI)-positive isolates exhibited a higher transfer frequency (10−4–10−5 transconjugants/donor) than traI(pAQU-IncA/C-SRI)-negative isolates (&lt
10−9). Conclusions These results suggest that mef(C)–mph(G) are coded on various vectors and are distributed among marine and wastewater bacteria in Asian countries. Vectors with traI(pAQU-IncA/C-SRI) play a role in the spread of mef(C)–mph(G).

DOI： 10.1016/j.jgar.2017.03.015

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media S.A.  

DOI： 10.3389/fmicb.2017.00014

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Microbial Ecology  

Extracellular DNA (exDNA) is released from bacterial cells through various processes. The antibiotic resistance genes (ARGs) coded on exDNA may be horizontally transferred among bacterial communities by natural transformation. We quantitated the released/leaked tetracycline resistance gene, tet(M) over time under grazing stress by ciliates and heterotrophic nanoflagellates (HNFs), and found that extracellular tet(M) (ex-tetM) increased with bacterial grazing. Separate microcosms containing tet(M)-possessing bacteria with ciliates or HNFs were prepared. The copy number of ex-tetM in seawater in the ciliate microcosm rapidly increased until 3 d after the incubation, whereas that in the HNF microcosm showed a slower increase until 20 d. The copy number of ex-tetM was stable in both cases throughout the incubation period, suggesting that extracellular ARGs are preserved in the environment, even in the presence of grazers. Additionally, ARGs in bacterial cells were constant in the presence of grazers. These results suggest that ARGs are not rapidly extinguished in a marine environment under grazing stress.

DOI： 10.1264/jsme2.ME17042

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media S.A.  

Aerobic anoxygenic phototrophic bacteria (AAnPB) rely on not only heterotrophic but also phototrophic energy gain. AAnPB are known to have high abundance in oligotrophic waters and are the major portion of the bacterial carbon stock in the environment. In a yearlong study in an aquaculture area in the Uwa Sea, Japan, AAnPB, accounted for 4.7 to 24% of the total bacteria by count. Since the cell volume of AAnPB is 2.23 � 0.674 times larger than the mean for total bacteria, AAnPB biomass is estimated to account for 10-53% of the total bacterial assemblage. By examining pufM gene sequence, a common phylogenetic AAnPB species was found in all sampling sites through the year. The common species and other season-specific species were phylogenetically close to unculturable clones recorded in the Sargasso Sea and Pacific Ocean. The present study suggests that the common species may be a cosmopolitan species with worldwide distribution that is abundant not only in the oligotrophic open ocean but also in eutrophic aquaculture areas.

DOI： 10.3389/fmicb.2016.01996

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Research Foundation  

Antimicrobials are widely used, not only for treating human infections, but also for treatment of livestock and in fish farms. Human habitats in Southeastern Asian countries are located in close proximity to aquatic environments. As such, the human populations within these regions are at risk of exposure to antimicrobial resistant bacteria, and thereby disseminating antimicrobial resistance genes (ARGs). In this study, we collected water samples from 15 sites (5 sites in Chao Phraya River, 2 sites at the mouth of Chao Phraya River, 3 sites in Ta Chin River, and 5 sites at city canals) and 12 sites (6 sites at city canals
2 sites at chicken farms
2 sites at pig farms
and 2 samples from sites at pig farms, which were subsequently treated at a biogas plant) in Thailand in 2013 and 2014, respectively. In total, 117 Aeromonas spp. were isolated from the water samples, and these organisms exhibited various antimicrobial susceptibility profiles. Notably, there was a significant correlation between the environmental concentration of tetracyclines and the rates of tetracycline resistance in the isolated Aeromonas spp.
however, both the concentration and rates of tetracycline resistance in samples derived from pig farms were higher than those of samples harvested from other aquatic environments. These findings suggest that the high concentrations of antimicrobials observed in these aquatic environments likely select for ARGs. Furthermore, they indicate that Aeromonas spp. comprise an effective marker for monitoring antimicrobial resistance in aquatic environments.

DOI： 10.3389/fmicb.2016.00710

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society of Microbial Ecology  

The persistence of the multi-drug resistance plasmids pAQU1 and IncFIB was examined in bacterial populations under very low selective pressure. We herein demonstrated that these plasmids stably remained not only in the original host, but also in a transconjugant, even after being in a non-culturable state. In seawater microcosms containing Photobacterium damselae 04Ya311 possessing pAQU1, no significant loss of pAQU1 was observed during a 30-d starvation period. The copy numbers of pAQU1 and IncFIB in E. coli were constant. The results of the present study suggest that these plasmids have the ability to remain among various bacteria under oligotrophic conditions with low antibiotic selection pressure.

DOI： 10.1264/jsme2.ME15122

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Verlag  

Antibiotic-resistant bacteria can be detected in pristine environments and animals. Tetracycline (TC) is frequently used for wide areas of veterinary medicine, which selects TC-resistant bacteria. The TC resistance genes are known from natural environments, and tet(M) is the broadest host range tet gene. Here, we report that TC-resistant bacteria and the TC resistance gene tet(M) were diverse in Adélie penguin intestines, even within a single penguin colony. Total bacterial counts were as high as 107 CFU g−1, and TC-resistant bacteria ranged from 1.4 × 102 to 6.6 × 103 CFU g−1 intestinal contents, which was 0–0.54 % of the total viable count. Phylogenetic affiliation of TC-resistant bacteria revealed a variety of Gram-positive and Gram-negative bacteria. The tet(M) gene was identified in 32.3 % of TC-resistant strains, and two tet(M) genotypes were identified within one penguin colony, suggesting various contamination origins of tet(M).

DOI： 10.1007/s00300-015-1732-x

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その他リンク： http://link.springer.com/article/10.1007/s00300-015-1732-x/fulltext.html

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

The biodegradation of proteins in seawater requires various proteases which are commonly thought to be mainly derived from heterotrophic bacteria. We, however, found that protists showed a high protease activity and continuously produced trypsin-type enzymes. The free-living marine heterotrophic ciliate Paranophrys marina together with an associated bacterium was isolated and used for microcosm incubation with different concentrations of killed bacteria as food for 10 days. The results showed that the co-existence of the ciliate with its associated bacterium produced a significant protease activity in both cell-associated and cell-free fractions while that in the associated bacterium only microcosm was negligible. The protease profiles are different between cell-associated and cell-free fractions, and a trypsin-type enzyme hydrolyzing Boc-Val-Leu-Lys-MCA was detected throughout the period in the presence of ciliates. This suggests that ciliates release proteases into the surrounding environment which could play a role in protein digestion outside cells. It has been previously suggested that bacteria are the major transformers in seawater. We here present additional data which indicates that protists, or at least ciliates with their specific enzymes, are a potential player in organic matter degradation in water columns.

DOI： 10.1016/j.marenvres.2015.06.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The aim of this study was to determine whether mef(C) and mph(G), originally found on the transferable multi-drug plasmid pAQU1 from Photobacterium damselae subsp. damselae isolated from seawater of a fish farm, are responsible for conferring macrolide resistance. Since these genes are localized head-to-tail on pAQU1 and only four nucleotides exist between them, the single- and combination-effect of these genes was examined. When mph(G) alone was introduced to Escherichia coli, the minimum inhibitory concentrations (MICs) against erythromycin, clarithromycin and azithromycin increased, whereas introduction of mef(C) alone did not influence macrolide susceptibility. Introduction of both mef(C) and mph(G) dramatically increased the MICs to the same three macrolides, i.e. &gt;512gml(-1), &gt;512gml(-1) and 128gml(-1) respectively. These results suggest that the macrolide phosphotransferase encoded by mph(G) is essential for macrolide resistance, while the efflux pump encoded by mef(C) is required for high-level macrolide resistance. The tandem-pair arrangements of the mef(C) and mph(G) genes were conserved on plasmids ranging in size from 240 to 350kb of the 22 erythromycin-resistant strains belonging to Vibrio and Photobacterium obtained from the fish farm. Sixteen of 22 plasmids ranged in size from 300 to 350kb. This is the first report of novel macrolide resistance genes originating from a marine bacterium.
Significance and Impact of the StudyIn this study, mef(C) and mph(G) were found to be novel macrolide-resistance genes, and this is the first report of macrolide-resistance genes originating from a marine bacterium. These genes may be responsible for previously reported cases of the emergence of erythromycin-resistant bacteria in aquaculture sites by an unknown mechanism. The introduction of the tandem arrangement of the mef(C) and mph(G) genes in Escherichia coli increased the MICs to erythromycin, clarithromycin and azithromycin, suggesting a novel mechanism conferring high-level macrolide resistance via combined expression of the efflux pump and macrolide phosphotransferase.

DOI： 10.1111/lam.12414

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その他リンク： http://orcid.org/0000-0003-2347-616X

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS INC  

Tributyltin (TBT) is one of the most toxic xenobiotics ubiquitous in the aquatic environment. Several reports have described the negative impact of TBT in living organisms, from bacteria to mammals. Over the world, TBT contamination has being described as a serious problem. Thus, it is imperative to decontaminate TBT polluted sites. Bioremediation strategies may constitute an alternative to conventional decontamination methods, benefiting from the microorganisms potential to metabolize xenobiotics. Several microorganisms among bacteria, fungus, and algae have been reported to possess the ability to resist and, in certain cases, degrade TBT in their simple and less toxic derivatives. Due their characteristics, some of those microorganisms have been used for bioremediation studies and to construct bioreporters to detect TBT in the environment. This review provides an overview regarding microbial TBT resistance, while focusing on TBT degradation and bioremediation. A comprehensive revision on the several applications of organotin compounds, adverse biological effects on living organisms, and information regarding the available TBT bioreporters is also included.

DOI： 10.1080/10643389.2014.924181

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Aerobic anoxygenic phototrophic bacteria (AAnPB) are bacteriochlorophyll a-containing photoheterotrophic organisms that rely on phototrophy and heterotrophy processes for energy acquisition. Here, we demonstrate the ubiquitous distribution of AAnPB in the Uwa Sea and their relatively larger cell size among members of the bacteria community. The contribution of AAnPB in terms of cell number to the total bacterial abundance ranged from 3.5 % to 7.9 %. The mean cell volume for AAnPB was 2.78 +/- A 0.72 times larger than the mean cell volume of the total bacteria. The ratio of the contribution of their biovolume to the total bacteria was estimated to be 9.7-22 %.

DOI： 10.1007/s10872-014-0267-z

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media S.A.  

Antibiotic resistant bacteria are ubiquitous in the natural environment. The introduction of e?uent derived antibiotic resistance genes (ARGs) into aquatic environments is of concern in the spreading of genetic risk. This study showed the prevalence of sulfonamide and tetracycline resistance genes, sul1, sul2, sul3, and tet(M), in the total bacterial assemblage and colony forming bacterial assemblage in river and estuarine water and sewage treatment plants (STP) in South Africa. There was no correlation between antibiotic concentrations and ARGs, suggesting the targeted ARGs are spread in a wide area without connection to selection pressure. Among sul genes, sul1 and sul2 were major genes in the total (over 10-2copies/16S) and colony forming bacteria assemblages (~10-1copies/16S). In urban waters, the sul3 gene was mostly not detectable in total and culturable assemblages, suggesting sul3 is not abundant. tet(M) was found in natural assemblages with 10-3copies/16S level in STP, but was not detected in colony forming bacteria, suggesting the non-culturable (yet-to-be cultured) bacterial community in urban surface waters and STP e?uent possess the tet(M) gene. Sulfamethoxazole (SMX) resistant (SMXr) and oxytetracycline (OTC) resistant (OTCr) bacterial communities in urban waters possessed not only sul1 and sul2 but also sul3 and tet(M) genes. These genes are widely distributed in SMXr and OTCr bacteria. In conclusion, urban river and estuarine water and STP e?uent in the Durban area were highly contaminated with ARGs, and the yet-to-be cultured bacterial community may act as a non-visible ARG reservoir in certain situations.

DOI： 10.3389/fmicb.2015.00796

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Tributyltin (TBT) is a biocide extremely toxic to a wide range of organisms, which has been used for decades in antifouling paints. Despite its global ban in 2008, TBT is still a problem of great concern due to the high levels trapped in sediments. Aeromonas molluscorum Av27 is a TBT degrading bacterium that was isolated from an estuarine system. We investigated the ability and the role of this bacterium on TBT degradation in this estuarine system, using a microcosm approach in order to mimic environmental conditions. The experiment was established and followed for 150 days. Simultaneously, changes in the indigenous bacterial community structure were also investigated. The results revealed a maximum TBT degradation rate of 28% accompanied by the detection of the degradation products over time. Additionally, it was observed that TBT degradation was significantly enhanced by the presence of Av27. In addition a significantly higher TBT degradation occurred when the concentration of Av27 was higher. TBT degradation affected the bacterial community composition as revealed by the changes in the prevalence of Proteobacteria subdivisions, namely the increase of Deltaproteobacteria and the onset of Epsilonproteobacteria. However, the addition of Av27 strain did not affect the dominant phylotypes. Total bacterial number, bacterial biomass productivity, 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) analyses also indicated alterations on the bacterial community structure over time, with bacteria non-tolerant to pollutants increasing their representativeness, as, for instance, the increase of the number of Alphaproteobacteria clones from 6% in the beginning to 12% at the end of the experiment. The work herein presented confirms the potential of Av27 strain to be used in the decontamination of TBT-polluted environments. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.envres.2014.04.031

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：FRONTIERS RESEARCH FOUNDATION  

Emergence of antibiotic-resistant bacteria in the aquaculture environment is a significant problem for disease control of cultured fish as well as in human public health. Conjugative mobile genetic elements (MGEs) are involved in dissemination of antibiotic resistance genes (ARGs) among marine bacteria. In the present study, we first designed a PCR targeting tral gene encoding essential relaxase for conjugation. By this new PCR, we demonstrated that five of 83 strains isolated from a coastal aquaculture site had tral-positive MGEs. While one of the five strains that belonged to Shewanella sp. was shown to have an integrative conjugative element of the SXT/R391 family (ICE VchMex-like), the MGEs of the other four strains of Vibrio spp. were shown to have the backbone structure similar to that of previously described in pAQU1. The backbone structure shared by the pAQU1-like plasmids in the four strains corresponded to a similar to 100-kbp highly conserved region required for replication, partition and conjugative transfer, suggesting that these plasmids constituted "pAQU group." The pAQU group plasmids were shown to be capable of conjugative transfer of tet(M) and other ARGs from the Vibrio strains to E. colt. The pAQU group plasmid in one of the examined strains was designated as pAQU2, and its complete nucleotide sequence was determined and compared with that of pAQU1. The results revealed that pAQU2 contained fewer ARGs than pAQU1 did, and most of the ARGs in both of these plasmids were located in the similar region where multiple transposases were found, suggesting that the ARGs were introduced by several events of DNA transposition into an ancestral plasmid followed by drug selection in the aquaculture site. The results of the present study indicate that the "pAQU group" plasmids may play an important role in dissemination of ARGs in the marine environment.

DOI： 10.3389/fmicb.2014.00152

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PUBLIC LIBRARY SCIENCE  

Persistence and dispersal of antibiotic resistance genes (ARGs) are important factors for assessing ARG risk in aquaculture environments. Here, we quantitatively detected ARGs for sulphonamides (sul1 and sul2) and trimethoprim (dfrA1) and an integrase gene for a class 1 integron (intI1) at aquaculture facilities in the northern Baltic Sea, Finland. The ARGs persisted in sediments below fish farms at very low antibiotic concentrations during the 6-year observation period from 2006 to 2012. Although the ARGs persisted in the farm sediments, they were less prevalent in the surrounding sediments. The copy numbers between the sul1 and intI1 genes were significantly correlated suggesting that class 1 integrons may play a role in the prevalence of sul1 in the farm sediments through horizontal gene transfer. In conclusion, the presence of ARGs may limit the effectiveness of antibiotics in treating fish illnesses, thereby causing a potential risk to the aquaculture industry. However, the restricted presence of ARGs at the farms is unlikely to cause serious effects in the northern Baltic Sea sediment environments around the farms.

DOI： 10.1371/journal.pone.0092702

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記述言語：英語   出版者・発行元：Oceanographic Society of Japan  

DOI： 10.1007/s10872-013-0212-6

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記述言語：英語   出版者・発行元：Oceanographic Society of Japan  

DOI： 10.1007/s10872-013-0216-2

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media S. A  

Proteins constitute the major portion of labile substances in the marine environment and are an important source of organic matter supporting marine ecosystems. However, previous studies have revealed that specific bacterial membrane proteins are refractory in the oceans. We here show by kinetic analyses of protease degradation activity using inactivated Pseudomonas aeruginosa (Pa) cells as a proteinaceous substrate that bacterial proteases are insufficient to completely hydrolyze proteins, which may partially cause the protein accumulation in seawater. Protease activity was monitored simultaneously in 8 microcosms subjected to differing conditions. Some Pa proteins were retained for 30 days in the presence of bacteria without protists, whereas the Pa proteins were completely disappeared in the presence of both, indicating that these proteins were substantially incorporated into protist biomass. Our result suggests that protists play an important role in the transformation of bacterial proteins in seawater. Our experiments also imply that the functional/taxonomic diversity should be taken into account when considering decomposition activity in marine environments.

DOI： 10.3389/fmars.2014.00069

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その他リンク： http://orcid.org/0000-0003-4041-100X

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Aeromonas molluscorum Av27 is an estuarine bacterium highly resistant to tributyltin (TBT). Also, the strain is able to degrade TBT into the less toxic compounds dibutyltin and monobutyltin. Therefore, this bacterium has potential to be employed in bioremediation processes. In this context, defining its biological safety is crucial. With that purpose a number of intrinsic characteristics, usually present/associated with virulent strains, were investigated. Few virulence factors were detected in strain Av27. For instance, a DNase gene is present, but it is not apparently expressed in vitro. Motility, adherence factor and phospholipase activity were also detected. Additionally, cytotoxicity to Vero cells was negative. Resistance to penicillin (10 mu g ml(-1)), amoxicillin/clavulanic acid (30 mu g ml(-1)) and cephalothin (30 mu g ml(-1)) and also to the vibriostatic agent O/129 was observed. Five plasmids (4, 7, 10, 100 kb and one greater than 100 kb) were identified. No Class I and II integrons were detected. Study of the optimal growth conditions showed that Av27 easily adapts to different environmental conditions. Overall, the results suggest that A. molluscorum Av27 can be considered safe to use to bioremediate TBT in contaminated environments.

DOI： 10.1007/s10482-013-9961-x

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記述言語：英語   出版者・発行元：US DEPT HEALTH HUMAN SCIENCES PUBLIC HEALTH SCIENCE  

BACKGROUND: There is growing concern worldwide about the role of polluted soil and water environments in the development and dissemination of antibiotic resistance.
OBJECTIVE: Our aim in this study was to identify management options for reducing the spread of antibiotics and antibiotic-resistance determinants via environmental pathways, with the ultimate goal of extending the useful life span of antibiotics. We also examined incentives and disincentives for action.
METHODS: We focused on management options with respect to limiting agricultural sources; treatment of domestic, hospital, and industrial wastewater; and aquaculture.
DISCUSSION: We identified several options, such as nutrient management, runoff control, and infrastructure upgrades. Where appropriate, a cross-section of examples from various regions of the world is provided. The importance of monitoring and validating effectiveness of management strategies is also highlighted. Finally, we describe a case study in Sweden that illustrates the critical role of communication to engage stake-holders and promote action.
CONCLUSIONS: Environmental releases of antibiotics and antibiotic-resistant bacteria can in many cases be reduced at little or no cost. Some management options are synergistic with existing policies and goals. The anticipated benefit is an extended useful life span for current and future antibiotics. Although risk reductions are often difficult to quantify, the severity of accelerating worldwide morbidity and mortality rates associated with antibiotic resistance strongly indicate the need for action.

DOI： 10.1289/ehp.1206446

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

With an increasing need for assessing the risk of aquaculture antibiotics, there has been growing interest in their fate and effect on sedimentary bacteria. Here we show the risk assessment for oxytetracycline (OTC) use in seawater and its subsequent transfer to sediment, and illustrate that the sediment bacterial community was stable against OTC at dosed concentrations. Water-sediment microcosm experiments were conducted to simulate quiescent aquaculture conditions. The sorption coefficient (K-d) was 12.3-44.2 mL/g, which is lower than the previous reports employing vigorous mixing. In a denaturing gradient gel electrophoresis (DGGE) analysis, the addition of OTC at 50 mu g/L into the water phase had little effect on the major sediment bacterial community structure. This finding suggests that low concentrations of OTC in the water phase - such as those used within many aquaculture operations - do not pose a high risk of causing major changes in environmental sediment bacterial community structures. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.etap.2013.03.013

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Seven sulfonamides, trimethoprim, five macrolides, lincomycin and three tetracyclines were measured in 150 water samples of sewage, livestock and aquaculture wastewater, and river and coastal waters, in five tropical Asian countries. The sum of the concentrations of the target antibiotics in sewage and heavily sewage-impacted waters were at sub- to low-ppb levels. The most abundant antibiotic was sulfamethoxazole (SMX), followed by lincomycin and sulfathiazole. The average concentration of SMX in sewage or heavily sewage-impacted waters was 1720 ng/L in Vietnam (Hanoi, Ho Chi Minh, Can Tho; n=15), 802 ng/L in the Philippines (Manila; n=4), 538 ng/L in India (Kolkata; n=4), 282 ng/L in Indonesia (Jakarta; n=10), and 76 ng/L in Malaysia (Kuala Lumpur; n=6). These concentrations were higher than those in Japan, China, Europe, the US and Canada. A predominance of sulfonamides, especially SMX, is notable in these tropical countries. The higher average concentrations, and the predominance of SMX, can be ascribed to the lower cost of the antibiotics. Both the concentration and composition of antibiotics in livestock and aquaculture wastewater varied widely. In many cases, sulfamethazine (SMT), oxytetracycline (OTC), lincomycin, and SMX were predominant in livestock and aquaculture wastewater. Both human and animal antibiotics were widely distributed in the respective receiving waters (i.e., the Mekong River and Manila Bay). SMT/SMX ratios indicate a significant contribution from livestock wastewater to the Mekong River and nearby canals, with an estimated similar to 10% of river water SMX derived from such wastewater. Mass flow calculations estimate that 12 tons of SMX is discharged annually from the Mekong River into the South China Sea. Riverine inputs of antibiotics may significantly increase the concentration of such antibiotics in the coastal waters. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.scitotenv.2013.02.027

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We analyzed polychlorinated biphenyls (PCBs), dichlorodiphenyl dichloroethane and its metabolites, hexachlorocyclohexanes (HCHs), polycyclic aromatic hydrocarbons (PAHs), and hopanes, in plastic resin pellets collected from nine locations along the Portuguese coast. Concentrations of a sum of 13 PCBs were one order of magnitude higher in two major cities (Porto: 307. ng/g-pellet
Lisboa: 273. ng/g-pellet) than in the seven rural sites. Lower chlorinated congeners were more abundant in the rural sites than in the cities, suggesting atmospheric dispersion. At most of the locations, PAH concentrations (sum of 33 PAH species) were ∼100 to ∼300. ng/g-pellet
however, three orders of magnitude higher concentrations of PAHs, with a petrogenic signature, were detected at a small city (Sines). Hopanes were detected in the pellets at all locations. This study demonstrated that multiple sample locations, including locations in both urban and remote areas, are necessary for country-scale pellet watch. © 2013 Elsevier Ltd.

DOI： 10.1016/j.marpolbul.2013.02.008

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microbiology Research Foundation  

DOI： 10.2323/jgam.59.47

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

We developed a simple aquatic microbial ecosystem model in order to examine potential effects of zinc on microorganisms and the related degradation of dissolved organic matter (DOM). The model is a combination of both a traditional food chain and a microbial loop. The traditional food chain is mainly composed of phytoplankton and zooplankton, whilst the microbial loop is composed of DOM, bacteria and bacterivorous protozoa. We incorporated the suppressive effect of zinc on the bacterial uptake of DOM and assessed the steady state responses of the model for various zinc concentrations. The analytical and numerical results of the model implied that either zooplankton or bacterivorous protozoa might be the most vulnerable group to excessive zinc load than bacteria, depending on the grazing preference of zooplankton between phytoplankton and bacterivorous protozoa. The sensitivity analyses supported that the microbial loop solely is more sensitive to zinc than the coupled system combining both the traditional food chain and the microbial loop. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.chemosphere.2012.09.014

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Research Foundation  

Recent evidence has shown that antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are ubiquitous in natural environments, including sites considered pristine. To understand the origin of ARGs and their dynamics, we must first define their actual presence in the natural bacterial assemblage. Here we found varying distribution profiles of sul genes in "colony forming bacterial assemblages" and "natural bacterial assemblages." Our monitoring for antibiotic contamination revealed that sulfamethoxazole (SMX) is a major contaminant in aquatic environments of Metro-Manila, which would have been derived from human and animal use, and subsequently decreased through the process of outflow from source to the sea. The SMX-resistant bacterial rate evaluated by the colony forming unit showed 10 to 86% of the total colony numbers showed higher rates from freshwater sites compared to marine sites. When sul genes were quantified by qPCR, colony-forming bacteria conveyed sul1 and sul2 genes in freshwater and seawater (10-5-10-2 copy/16S) but not sul3. Among the natural bacterial assemblage, all sul1, sul2, and sul3 were detected (10-5-10-3 copy/16S), whereas all sul genes were at an almost non-detectable level in the freshwater assemblage. This study suggests that sul1 and sul2 are main sul genes in culturable bacteria, whereas sul3 is conveyed by non-culturable bacteria in the sea. As a result marine bacteria possess sul1, sul2 and sul3 genes in the marine environment. © 2013 Suzuki, Ogo, Miller, Shimizu, Takada and Siringan.

DOI： 10.3389/fmicb.2013.00102

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INTER-RESEARCH  

Protein biodegradation in the marine environment is caused by proteases derived from various organisms, including bacteria, which are considered to be a major source of these enzymes. We investigated the succession of bacterial proteases in seawater to determine the variation in protease activity over time. The potential activities of proteolytic enzymes in stored seawater and isolated bacteria were studied using 19 different synthetic oligopeptide substrates for aminopeptidase, trypsin, chymotrypsin and elastase. In time-course experiments carried out over 112 d, aminopeptidase activity increased, whereas trypsin activity decreased over time. Amino peptidase activity was mainly found in unfiltered seawater containing bacterial cells, whereas trypsin activity was mainly found in 0.2 mu m seawater filtrates. Individual bacterial isolates showed different proteolytic properties but all exhibited aminopeptidase activity. Members of the Gammaproteobacteria and Bacteroidetes showed high trypsin and chymotrypsin activities. Based on these results, we conclude that protein degradation in seawater occurs via the combined action of various bacterial proteases.

DOI： 10.3354/ame01618

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Vanadium is a contaminant from steel additive and ship fuel in coastal and port areas, and its effect on marine microbes remains largely unknown. We showed that vanadium accelerates transfer of the tetracycline resistance gene tet(M) from Photobacterium to Escherichia coli, and found a positive correlation between the concentration of vanadium in natural marine sediment and the rate of oxytetracycline resistance. These results suggest the possibility that vanadium may play a role in the preservation and horizontal transfer of antibiotic resistance genes in the marine environment.

DOI： 10.1111/j.1574-6968.2012.02653.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The effect of tributyltin (TBT) on growth and metabolic activity of three estuarine bacteria with different TBT resistance profiles was investigated in an organic-rich culture medium (TSB) and in phosphate buffered saline (PBS) buffer. Exposure to TBT was assessed by determining its effect on growth (OD600 nm measurement), bacterial productivity (leucine incorporation), viability (CFU counts), aggregation and cell size (from Live/Dead analysis), ATP and NADH concentrations. TBT exposure resulted in decrease of bacterial density, cell size, and metabolic activity. In addition, cell aggregates were observed in the TBT-treated cultures. TBT strongly affected bacterial cell metabolism and seemed to exert an effect on its equilibrium, interfering with cell activity. Also, TBT toxicity was lower when cells were grown in TSB than in PBS, suggesting that a nutrient-rich growth medium can protect cells from TBT toxicity. This study contributes to our understanding of the TBT-resistant cell behavior reflected in its physiology and metabolic activity. This information is of utmost importance for further studies of TBT bioremediation. (C) 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.

DOI： 10.1002/tox.20605

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：FRONTIERS RESEARCH FOUNDATION  

Southeast Asia has become the center of rapid industrial development and economic growth. However, this growth has far outpaced investment in public infrastructure, leading to the unregulated release of many pollutants, including wastewater-related contaminants such as antibiotics. Antibiotics are of major concern because they can easily be released into the environment from numerous sources, and can subsequently induce development of antibiotic-resistant bacteria. Recent studies have shown that for some categories of drugs this source-to-environment antibiotic resistance relationship is more complex. This review summarizes current understanding regarding the presence of quinolones, sulfonamides, and tetracyclines in aquatic environments of Indochina and the prevalence of bacteria resistant to them. Several noteworthy findings are discussed: (1) quinolone contamination and the occurrence of quinolone resistance are not correlated; (2) occurrence of the su/ sulfonamide resistance gene varies geographically; and (3) microbial diversity might be related to the rate of oxytetracycline resistance.

DOI： 10.3389/fmicb.2012.00067

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MICROBIOL RES FOUNDATION  

A tributyltin (TBT) resistance gene was isolated from the TBT-resistant marine origin bacterium Pseudomonas aeruginosa 25W. This gene was identical to PA0320 deposited in the P. aeruginosa PAO1 database (http://www.pseudomonas.com). The deduced amino acid sequence of PA0320 appears to be homologous to the YgiW proteins of Escherichia coli and Salmonella enterica. The deletion mutant of PA0320 showed a reduction of growth rate in the presence of TBT. A susceptibility test to cadmium, mercury, hydrogen peroxide and acidic pH in the deletion mutant showed an increasing susceptibility to them. PA0320 plays a certain role in stress tolerance against TBT as well as in stressors producing reactive oxygen species.

DOI： 10.2323/jgam.58.283

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The ubiquitous application and release of antibiotics to the environment can result in bacterial antibiotic resistance, which in turn can be a serious risk to humans and other animals. Southeast Asian countries commonly apply an integrated recycling farm system called VAC (Vegetable, Aquaculture and Caged animal). In the VAC environment, antibiotics are released from animal and human origins, which would cause antibiotic-resistant bacteria (ARB). This study evaluated occurrence of ARB in the VAC environment in northern Vietnam, with quantitative analysis of antibiotic pollution. We found that sulfonamides were commonly detected at all sites. In dry season, while sulfamethazine was a major contaminant in pig farm pond (475-6662 ng/l) and less common in city canal and aquaculture sites, sulfamethoxazole was a major one in city canal (612-4330 ng/l). Erythromycin (154-2246 ng/l) and clarithromycin (2.8-778 ng/ml) were the common macrolides in city canal, but very low concentrations in pig farm pond and aquaculture sites. High frequencies of sulfamethoxazole-resistant bacteria (2.14-94.44%) were found whereas the occurrence rates of erythromycin-resistant bacteria were lower (&lt;0.01-38.8%). A positive correlation was found between sulfamethoxazole concentration and occurrence of sulfamethoxazole-resistant bacteria in dry season. The sulfamethoxazole-resistant isolates were found to belong to 25 genera. Acinetobacter and Aeromonas were the major genera. Twenty three of 25 genera contained sul genes. This study showed specific contamination patterns in city and VAC environments and concluded that ARB occurred not only within contaminated sites but also those less contaminated. Various species can obtain resistance in VAC environment, which would be reservoir of drug resistance genes. Occurrence of ARB is suggested to relate with rainfall condition and horizontal gene transfer in diverse microbial community. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.scitotenv.2011.04.030

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPANESE SOC MICROBIAL ECOLOGY, DEPT BIORESOURCE SCIENCE  

Fluoroquinolone antibiotics (FQs) have been used worldwide for chemotherapy, animal husbandry, and aquaculture, and the occurrence of FQ-resistant (FQs(r)) bacteria in natural environments has been reported. Plasmid-mediated transferable quinolone resistance (PMQR) genes are suspected to originate from the chromosomes of water-dwelling bacteria. However, the occurrence of and the potential reservoir of FQs(r) bacteria and PMQR genes in aquatic environments have not been elucidated. In this study, we detected FQs(r) bacteria and PMQR genes in aquatic environments in Thailand and Vietnam, and measured FQ contamination. Levels of contamination were greater Thailand (avg. 5130, max 46100 ng L(-1)) than in Vietnam (avg. 235, max 1130 ng L(-1)); however, the occurrence of FQs(r) bacteria was higher in Vietnam (similar to 15%) than in Thailand (similar to 7.0%), suggesting that contamination by FQs is not directly linked to the development of FQs(r) bacteria. Diverse taxonomic groups of FQs(r)-bacteria were identified, and one of the PMQR genes, qnrB, was detected from bacteria of environmental origin, not enteric bacteria. This suggests that the environmental bacteria are a potential reservoir of antibiotic resistance determinants even at un-contaminated sites.

DOI： 10.1264/jsme2.ME10204

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The prophylactic and therapeutic use of tetracyclines in aquaculture has been shown to contribute to the spread of tetracycline resistance in the environment In this work, the prevalence of four different tetracycline-resistance genes, tetA, tetC, tetH, and tetM, in sediments from four aquaculture farms and their surroundings in the Baltic Sea was monitored by quantitative polymerase chain reaction (qPCR). The presence of three additional tetracycline-resistance genes (tetE, tetG, and tetW) was studied qualitatively by standard PCR, and the amount of bioavailable tetracyclines and total amounts of tetracycline and oxytetracycline in samples were also measured. None of the farms were using tetracycline at the time of the sampling and one of the farms had stopped all antibiotic use six years prior to the first sampling. Two of the farms were sampled over four successive summers and two were sampled once. Our results showed greater copy numbers of tetA, tetC, tetH, and tetM at the farms compared to pristine sites and demonstrated the presence of tetE, tetG, and tetW genes in the sediments under aquaculture farms at most sampling times. However, no resistance genes were found in samples collected 200 m from any of the farms. None of the samples contained therapeutically active concentrations of tetracyclines at any of the sampling times, suggesting that the increase in the prevalence of tetracycline resistance genes is caused by the persistence of these genes in the absence of selection pressure.

DOI： 10.1021/es102725n

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INTER-RESEARCH  

To understand the role of zinc (Zn) in the biogeochemical cycle in coastal environments, we examined the bacterial remineralisation of dissolved organic matter (DOM) with 2 composite experiments using microcosms supplemented with Zn. In Expt 1, using samples collected from 2 stations in the Seto Inland Sea, Japan, we found that a decrease in DOM due to bacterial remineralisation during a 14 d experimental period had negative responses to Zn at both sites, but we found an inhibitory effect on bacterial abundance only at a station in the western part of the Seto Inland Sea. In Expt 2, comparison of the response of the remineralisation process to Zn among 3 kinds of organic substrate showed that Zn has little effect on 2 authentic standards (laminarin and bovine serum albumin) and that remineralisation of DOM originating from natural seawater was significantly suppressed by the addition of Zn. Based on the regression curves, we estimated the potential impact of Zn on the remineralisation of DOM. At a water quality standard of Zn concentration (86 mu g Zn l(-1)), DOM concentrations at the end of the experimental period (Day 14) increased 2.4 to 6.9%, and turnover time prolonged with a timescale of weeks to months. These potential shifts induced by Zn suggest that the allochthonous input of Zn into the coastal environment leads to suppression of energy flow in the microbial loop and enhances transport of DOM from coastal to offshore areas.

DOI： 10.3354/ame01481

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Microbial degradation and utilization of proteins derived from bacterial detritus were investigated in a microcosm experiment using Pseudomonas aeruginosa detritus as a substrate. To assess the effects of natural marine microbial communities on degradation and utilization of protein derived from P. aeruginosa cells, four microcosms were prepared: natural seawater (containing the natural microbial community) with P. aeruginosa detritus (N+Pa), autoclaved seawater with P. aeruginosa detritus (A+Pa), natural seawater (N) and autoclaved seawater (A) without adding anything as a control. The numbers of total and growing bacterial cells, protease activity, and transition of P. aeruginosa proteins were monitored in the four microcosms. Changes in the numbers of total and growing bacterial cells and protease activities indicated that bacterial detritus significantly stimulated the microbial community in the microcosms. Both the surviving P. aeruginosa in A+Pa and natural microbial community in N+Pa microcosms were able to degrade and utilize P. aeruginosa detritus; however, the community in N+Pa including various microbes maintained high activity longer, indicating that diversity is an important factor in keeping the community active. Even under the very high protease activity in N+Pa, 39-kDa and 48-kDa proteins from P. aeruginosa remained in the microcosm during the entire experiment (150 days). Immunoblotting suggested the 48-kDa protein was an intact molecule of OprP, which had been detected from the dissolved fraction of natural seawater in previous studies. This result suggests that the protein molecules that had been detected from natural seawater actually had a high tolerance to microbial degradation.

DOI： 10.1007/s10872-010-0043-7

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL PUBLISHING, INC  

P&gt;Pseudomonas aeruginosa is an opportunistic pathogen, and ubiquitously found in natural environments. However, details on difference between clinical and environmental isolates have not been reported enough. In this study, we defined existence of marine specific genogroup and different drug susceptibility among isolates from clinical, river and coastal seawaters. Pseudomonas aeruginosa were isolated by using cetrimide kanamycin nalidixic acid agar media and incubation at 42 degrees C, which was specific selection method of this bacterium from the natural aquatic samples. Pulse field gel electrophoresis analysis showed that the levels of genetic variation within P. aeruginosa were different among environmental sites. Pulse field gel electrophoresis also showed a lower diversity within P. aeruginosa in the coastal waters; and coastal strains isolated different sampling points were positioned closely in the same cluster. Most of the aquatic isolates were sensitive to most of the drugs tested and 'intermediate' to panipenem on the contrast to the clinical isolates, suggesting that the clinical use of antibiotics affect significantly to the emergence of the drug-resistant P. aeruginosa.

DOI： 10.1111/j.1758-2229.2010.00178.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organo-chlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs; showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.marpolbul.2009.06.014

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

The effect of water-surface discharge on the inactivation of Bacillus subtilis ATCC6633 in water was examined by using a very short high-voltage pulse generator. The surviving number of spore cells at 10(4) CFU/ml in initial concentration exponentially decreased with increasing discharge-treatment time. The input energy into the water-surface discharge under an O-2 gas flow for reduction in the survival number to 10% was lower than that under an air flow because many oxidation agents such as ozone and OH radical were produced under the O-2 gas flow.
The input energy density for the one-tenth reduction depended not only on the spore state but also on the initial cell concentration. The input energy for the high-concentration spore cells (10(7) CFU/ml) was much higher than that for the low-concentration spore cells (10(4) CFU/ml). Cellular proteins and DNA were degraded by a 30-min discharge treatment of vegetative cells, whereas DNA of the high-concentration spore cells was relatively resistant.

DOI： 10.1271/bbb.90153

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

The transferability of the tetracycline (TC) resistance gene tet(M) from marine bacteria to human enteric bacteria was examined by a filter-mating method. Vibrio spp., Lactococcus garvieae, Bacillus spp., Lactobacillus sp., and Paenibacillus sp. were used as donors, and Escherichia coli JM109 and Enterococcus faecalis JH2-2 were used as recipients. The combination of Vibrio spp. and E. coli resulted in 5/68 positive transconjugants with a transfer rate of 10(-7) to 10(-3); however, no transfer was observed with E. faecalis. In case of L. garvieae and E. faecalis, 6/6 positive transconjugants were obtained with a transfer rate of 10(-6) to 10(-5); however, no transfer was observed with E. coli. The tet(M) gene of Bacillus, Lactobacillus, and Paenibacillus were not transferred to either E. coli or E. faecalis. tet(M) transfer was confirmed in positive E. coli and E. faecalis transconjugants by polymerase chain reaction (PCR) and Southern hybridization. All the donor strains did not harbor plasmids, while they all harbored transposon Tn916. In the transconjugants, the transposon was not detected by PCR, suggesting the possible transfer of tet(M) from the marine bacterial chromosome to the recipient chromosome. This is the first report to show that tet(M) can be transferred from marine bacteria to human enteric bacteria in a species-specific manner.

DOI： 10.1007/s11274-009-0004-8

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MICROBIOLOGICAL SOCIETY KOREA  

Distribution of marine type of Aquabirnavirus (MABV) was examined in shellfish and fish from Okinawa and Ishigaki Islands, Japan, where water temperature is higher than 25A degrees C through the year. Genome detection and virus isolation were performed for shellfish and fish samples, and the results revealed the prevalent distribution of MABV in diverse species in the area, although isolation was not frequently. Detection rate of MABV genome in bivalves was higher than gastropods, which was similar result to former report in mainland of Japan. Furthermore, the unique five-nucleotide deletion was found with a high rate of occurrence in the MABV genome from shellfish and fish. This study showed distribution status of MABV in organisms in subtropical waters by wide monitoring, and discovered new genome variation in VP2/NS region of this virus.

DOI： 10.1007/s12275-008-0250-8

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

To assess the presence and distribution of the sul genes (sul1, sul2, and sul3) and plasmids in human-mediated environments of north Vietnam, we examined a total of 127 sulfonamide-resistant (SR) bacterial isolates from four shrimp ponds (HNAQs), a city canal (HNCs) and three fish ponds that received wastewater directly from swine farms (HNPs). Results from the SR isolates revealed that sul genes were most frequently detected in the HNPs (92.0%), followed by HNCs (72.0%), and the HNAQs (43.0%). Among the sul genes detected, sul1 was the most prevalent gene in all three environments (57.0,33.0 and 60.0% in HNPs, HNAQS, and HNCs, respectively) followed by sul2 (51.0, 19.0, and 20.0%, respectively) and sul3 (14.0, 6.0, and 8.0%, respectively). All combinations of paired different sul genes were detected, with the combination between sul1 and sul2 being the most frequent in all three environments (20.0, 8.0, and 8.0% in HNPs, HNAQs, and HNCs, respectively). The combination of three sul genes was detected at low frequencies (2-3%) in the HNPs and HNAQs, and was absent in the HNCs. The sul genes were more frequently located on the chromosome than on plasmids. The identification of SR isolates positive for the sul genes and plasmids showed that Acinetobacter was the most dominant. our study revealed that the sul genes were common in SR bacteria from the aquatic environments we examined from northern Vietnam. Wastewater from swine farms might be "hot spots" of the sul genes and plasmids and may be reservoirs for the exchange of the sul genes among bacteria. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.scitotenv.2008.06.023

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

DOI： 10.1093/jac/dkn209

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The tetracycline (TC) resistance gene team) was monitored in bacteria isolated from Japanese coastal and off-shore marine sediments. The high rate of occurrence of TC resistant (TC(r)) bacteria (120 mu g mL(-1) TC) was observed at frequency ranges between 0.0-0.08% in Tokyo Bay, 1.67-1.82% in Sagami Bay and 0.0-4.35% in the open Pacific Ocean. The tet(M) gene was PCR amplified from the TCr isolates, showing 127 of 209 isolates (60.8%) as positive. The rate of occurrence of tet(M)) was between 32.0-96.0%, 21.1-28.0% and 0.0-83.3% in the isolates from Tokyo Bay, Sagami Bay and the open Pacific Ocean, respectively. The team) positive isolates belonged to 4 orders of bacteria. Bacillales was the most dominant order (121 strains) among team) possessing bacteria, followed by Actinomycetales (three strains), Flavobacteriales (one strain) and Pseudomonadales (one strain). This indicates that team) is present in various bacterial species and suggests that marine sediments are a natural reservoir of the team) gene. Nucleotide sequence of the team) revealed that two genotypes of team) were found in the bacteria. The two genotypes were placed in genetically distant branches of the phylogenetic tree, suggesting that the two tet(M)s have different origins.

DOI： 10.1021/es702986y

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

In aquatic environments extracellular enzymes are bound to microbial cells or exist in a free and adsorbed state. Various filters have been used to fractionate these enzymatic activities, but enzymes may be readily adsorbed onto some materials, and such adsorption can induce errors in the estimation of enzymatic activity. In this study we examined three filters to determine the most suitable filter for fractionation when estimating proteolytic enzyme activity in seawater. We found that the polycarbonate Nuclepore membrane, widely used for size fractionation because of its pore-size accuracy, was the most favorable for this purpose, even though it adsorbed slightly more enzymes than the low-protein-binding polyethersulfone membrane. We also found that trypsin- and chymotrypsin-type enzymes were more easily adsorbed than aminopeptidases.

DOI： 10.1007/s10872-008-0029-x

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING  

The coding regions for the major epitopes of structural protein VP2 (vp2e) and structural protein VP3 were amplified from marine birnavirus (MABV) cDNA and efficiently expressed as glutathione S-transferase (GST) fusion proteins in Escherichia coli. Polyclonal antibodies against VP2e and VP3 were raised in rabbits and fish using the purified proteins of GST/VP2e and GST/VP3. The rabbit anti-serum against VP3 was more sensitive than the rabbit anti-VP2e serum in detecting virus in MABV-infected fish, while fish anti-VP2e serum showed a stronger neutralization response than fish anti-VP3 serum.

DOI： 10.1111/j.1365-2761.2008.00909.x

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INTER-RESEARCH  

We analyzed potential activities of different proteolytic enzymes in size-fractionated seawater, and estimated the contribution of each size fraction (&lt; 0.2, 0.2-0.8, 0.8-5, and &gt; 5 mu m) to the bulk hydrolytic activity of each enzyme in the seawater. The activity of leucine-aminopeptidase was highly attributed to cell-associated size fractions, while the contribution of the dissolved fraction (&lt; 0.2 mu m) to the bulk activity was only 10 to 30 %. In contrast, the contribution of the dissolved fraction to the activities of the trypsin- and chymotrypsin-type endopeptidases was as high as 40 to 80 % of their bulk activities measured in unfiltered seawater. These results indicated the potential importance of free proteolytic enzymes in seawater, especially for endopeptidases. Significant enzymatic activity in the dissolved fraction was also detected from experiments with isolated bacteria, suggesting that direct secretion of proteases from marine bacteria into surrounding water could be at least one of the sources of the dissolved proteolytic enzymes in seawater. Generally, the natural bacterial community of seawater was able to hydrolyze all of the 16 tested substrates, but at different rates. Selected members of the community (3 bacterial isolates and Synechococcus) hydrolyzed only one or a few of the applied substrates, and the substrate preference varied among the strains. These results suggest that natural bacterial communities are composed of a great variety of bacterial species with different (specific) enzymatic properties, including dissolved endopeptidases and cell-associated aminopeptidase. The combined activities of these enzymes are responsible for an effective degradation and re-use of high molecular weight organic matter at the community level.

DOI： 10.3354/ame01169

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.marenvres.2007.06.006

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPANESE SOC MICROBIAL ECOLOGY, DEPT BIORESOURCE SCIENCE  

Spatial monitoring of tetracycline (TC)-resistant bacteria in sediments of the Mekong River watershed revealed that the main waterway showed a high occurrence rate of TC-resistant bacteria, whereas Tonle Sap Lake and the Sai Gon estuary did not. The Shannon index (H'), an indicator of ecological diversity, was calculated from denaturing gradient gel electrophoresis (DGGE) profiles, which indicated that the main waterway of the Mekong River had high microbial diversity (high H') compared to Tonle Sap Lake and the Sai Gon estuary; this diversity was positively correlated with the occurrence rate of TC-resistant bacteria. Analysis of ribosomal protection protein (RPP) genes tet(M), tet(S) and tet(W) in the same area also revealed that high diversity was positively correlated with the occurrence rate of RPP genes, suggesting that RPP genes are well conserved across various bacterial species. Further evidence of different genotypes of tet(M) suggests that the drug resistance genes likely have various origins, and are mixed in the sediment. Sediments in this area are therefore potential reservoirs of drug resistance genes.

DOI： 10.1264/jsme2.23.149

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ZOOLOGICAL SOC JAPAN  

A serious disease of the ascidian Halocynthia roretzi has been spread extensively among Korean aquaculture sites. To reveal the cause of the disease and establish a monitoring system for it, we constructed a cDNA microarray spotted with 2,688 cDNAs derived from H. roretzi hemocyte cDNA libraries to detect genes differentially expressed in hemocytes between diseased and non-diseased ascidians. We detected 21 genes showing increased expression and 16 genes showing decreased expression in hemocytes from diseased ascidians compared with those from non-diseased ascidians. RT-PCR analyses confirmed that the expression levels of genes encoding astacin, lysozyme, ribosomal protein PO, and ubiquitin-ribosomal protein L40e fusion protein were increased in hemocytes from diseased ascidians, while those of genes encoding HSP40, HSP70, fibronectin, carboxypeptidase and lactate dehydrogenase were decreased. These genes were expressed not only in hemocytes but also in various other tissues in ascidians. Furthermore, the expression of glutathione-S transferase omega, which is known to be up-regulated in H. roretzi hemocytes during inflammatory responses, was strongly increased in hemocytes from diseased ascidians. These gene expression profiles suggest that immune and inflammatory reactions occur in the hemocytes of diseased ascidians. These genes will be good markers for detecting and monitoring this disease of ascidians in Korean aquaculture sites.

DOI： 10.2108/zsj.24.1231

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPANESE SOC MICROBIAL ECOLOGY, DEPT BIORESOURCE SCIENCE  

We found increased numbers of oxytetracycline (OTC)-resistant bacteria in sediment and seawater around a marine aquaculture site after OTC therapy. Samples were collected at an aquaculture site along the coast of the Seto Inland Sea, Japan in 2004. In April, the percentage of bacteria resistant to 60 mu g mL(-1) OTC in the surface sediment was 6.8%-20.0%. The percentages increased during OTC therapy in the summer reaching 53.3%-60.7% in September. Ninety-two days after drug cessation, the percentages decreased to below 22.9%. Tet(M)-positive bacteria were detected in the sediment and seawater samples. Tet(M) was evident in both Gram-positive and Gram-negative bacteria from various genera, and was newly identified in Paenibacillus, Sporosarcina, Shewanella, and Pseudoalteromonas. The dominant tet(M)-positive isolates were strains of Vibrio suggesting that this genus is an important reservoir for tet(M) in the marine environment. Two different alleles were found, tet(M)-A and tet(M)-B, each in isolates from five genera. The data suggests drug therapy used in the aquaculture acted as a selective pressure promoting increased numbers of resistant bacteria.

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

The ribosomal protection proteins (RPPs) mediate the resistance to tetracycline (TC) in Gram-positive and Gram-negative bacteria. The RPPs display sequence similarity to translation elongation factors, EF-G/EF-2 and EF-Tu/EF-1 alpha. To determine the evolutionary origin of the RPPs, we constructed a composite phylogenetic tree of the RPPs, EF-G/EF-2 and EF-Tu/EF-1 alpha. This tree includes two universal trees for the EF-G/EF-2 and EF-Tu/EF-1 alpha, which form clusters corresponding to the respective two groups of proteins from three superkingdoms. The cluster of RPPs was placed at a point between the EF-G/EF-2 and EF-Tu/EF-1 alpha clusters. The branch length (substitutions/site) between the node for the RPP cluster and the primary divergence of the RPPs was statistically shorter than that between the node for this cluster and the primary divergence in the EF-G/EF-2 cluster. This indicates that the RPPs derived through duplication and divergence of the ancient GTPase before the divergence of the three superkingdoms. Furthermore, this suggests the RPPs' extant function occurred before the streptomycetes that include the TC-producing strains. Therefore, the RPPs evolved independent of the presence of TCs and serve a function other than antibiotic resistance. The RPPs may provide ribosomal protection against other chemical substances in the environment.

DOI： 10.1007/s00239-007-9006-z

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Tributyltin (TBT) is organotin compound that is toxic to aquatic life ranging from bacteria to mammals. This study examined the concentration of TBT in sediment from and near the Mekong River and the distribution of TBT-resistant bacteria. TBT concentrations ranged from &lt;2.4 to 2.4 ng/g (dry wt) in river sediment and &lt;2.4-15 ng g(-1) (dry wt) in harbor sediment. Viable count of total bacteria ranged from 2.0 x 10(4) to 1.4 x 10(7) cfu/g, and counts of TBT-resistant bacteria ranged &lt;1.0 x 10(2) to 2.5 x 10(4) cfu/g. The estimated occurrence rate of TBT-resistant bacteria ranged from &lt;0.01 to 34% and was highest in upstream sites in Cambodia. The occurrences of TBT in the sediment and of TBT-resistant bacteria were unrelated, and chemicals other than TBT might induce TBT resistance. TBT-resistant bacteria were more abundant in the dry season than in the rainy season. Differences in the selection process of TBT-resistant bacteria between dry and rainy seasons were examined using an advection-diffusion model of a suspended solid (SS) that conveys chemicals. The estimated dilution-diffusion time over a distance of 120 km downstream from a release site was 20 days during dry season and 5 days during rainy season, suggesting that bacteria at the sediment surface could be exposed to SS for longer periods during dry season. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.chemosphere.2007.03.033

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING  

Seasonal changes in the infection state of marine birnavirus (MABV) in Japanese flounder Paralichthys olivaceus and in rearing sea water are described. Sea water and 10-11 healthy fish were sampled monthly from April 2002 to February 2003. The MABV genome was detected throughout the year in &gt; 80% of the fish examined at each sampling. The virus was isolated from the liver, kidney, and spleen, but not from the brain. The detection rate in each organ increased from April to October, and then decreased. Detection of virus antigen by the indirect fluorescent antibody technique also showed that the virus was present from spring to autumn (June-September) in the liver, kidney, and spleen, but not the brain. Sequence analysis of the MABV genome at the VP2-NS region revealed two specific mutations compared to the standard yellowtail strain (Y-6). It is suggested that the infection state of MABV in Japanese flounder changes to a latent or persistent infection after autumn. MABV was detected in sea water between September and February, suggesting that virus particles in the environment are relatively higher during cool seasons.

DOI： 10.1111/j.1444-2906.2007.01374.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING  

Recently, a serious disease spread extensively in aquaculture sites of the ascidian Halocynthia roretzi in Korea. To understand circumstances of ascidians in Korean aquaculture sites, residue levels of organotin compounds were analyzed, and detection of a marine birnavirus (MABV) in tissues of H. roretzi was attempted. Korean H. roretzi showed high concentrations of butyltins (mono, di, and tributyltins), especially in the gill, hepatopancreas, and digestive tract. However, there was no significant difference in the residues of butyltins in the hepatopancreas between diseased and non-diseased ascidians. The positive rate of MABV detection was high in the hepatopancreas, but also no significant difference was observed between diseased and non-diseased individuals. These observations suggest that an accumulation of tributyltin and a latency of MABV in H. roretzi tissues does not directly relate to the occurrence of the disease.

DOI： 10.1111/j.1444-2906.2007.01332.x

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

We investigated the distribution and diversity of tetracycline resistance genes encoding ribosomal protection proteins (RPPs) in river and channel sediments of the Mekong Delta in Vietnam. The sediment samples were taken from nine sites in the Hau River in southern Vietnam and from 1 site in a channel in Can Tho City in May 2004 using an Ekman-Birge sediment surface sampler. The RPP genes were amplified using PCR with DNA templates obtained directly from the sediments. The tet(M), tet(S), and tet(W) genes were detected by PCR in most sediment samples. Denaturing gradient gel electrophoresis analysis of these genes and sequencing of the resulting bands showed that tet(S) and tet(W) had only one genotype each, but that tet(M) had at least two, which were tentatively called type 1 and type 2. Type 1 tet(M) was identical to the gene encoded in various plasmids and transposons of gram-positive and gram-negative bacteria, and type 2tet(M) was similar to the gene encoded in Tn1545 of Enterococcus faecalis (99% identity, 170 bp/171 bp). This study showed that various RPP genes were widely distributed in the river and channel sediments of the Mekong Delta.

DOI： 10.1111/j.1574-6941.2006.00244.x

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MICROBIOLOGY SOC KOREA  

In this study we examined the multi-drug resistance profiles of the tetracycline (TC) resistant genus Vibrio to determine its susceptibility to two beta-lactams, ampicillin (ABPC), and mecillinam (MPC), as well as to macrolide, erythromycin (EM). The results showed various patterns of resistance among strains that were isolated from very close geographical areas during the same year, suggesting diverse patterns of drug resistance in environmental bacteria from this area. In addition, the cross-resistance patterns suggested that the resistance determinants among Vibrio spp. are acquired differently within the sediment and seawater environments.

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

The degradation of tributyltin (TBT) and changes of bacterial number and community structures were investigated in microcosms using the sediment collected from the Mekong River, Vietnam. Concentrations of TBT in sediments were less than 0.62 ng/g (dry wt), lower than those reported from other areas. TBT-resistant bacteria were found in the three sampling sites, and the occurrence rates were 11-16% out of the total viable count. In this Microcosm experiment, initial concentration of TBT [1.0-1.4 mu g/g (dry wt)] decreased to 0.6 mu g/g (dry wt) during 150 days, whereas that in the control microcosm with autoclaved sediment did not change, indicating that Mekong River sediment contains high TBT-degrading activity by microorganisms. The occurrence of TBT-resistant bacteria and the bacterial community structures monitored by denaturing gradient gel electrophoresis were almost the same between test and control groups, indicating that the addition of TBT had little influence on microbial community structure. Mekong River sediment seems to have a stable microbial community against TBT pollution.

DOI： 10.1007/s00248-006-9079-z

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MICROBIOLOGY SOC KOREA  

The tributyltin (TBT)-resistant bacterium, Pseudomonas aeruginosa 25W, which was isolated in seawater from the Arabian Sea, was subjected to transcriptome analysis in the presence of high concentrations of TBT. Only slight effects were observed at TBT concentration of 50 mu M, but exposure to 500 mu M resulted in the upregulation of 6 genes and the downregulation of 75. Among the 75 downregulated genes, 53% (40 out of 75) were of hypothetical function, followed by 14 transcriptional regulation- and translation-associated genes. The results of this study indicated that although the 25W strain was highly resistant to TBT, high concentrations of TBT result in toxic effect on the transcriptional and translational levels. The target genes likely belong to a specific category of transcription- and translation-associated genes rather than to other gene categories.

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

VP5 is a 15-kDa nonstructural protein encoded by a small open reading frame in 5'-terminal of segment A of the Marine Birnavirus ( MABV) ( strainY-6) genome. Comparisons of the amino acid sequence of the VP5 with other Bcl-2 family member proteins indicated that the VP5 protein contains Bcl-2 homology (BH) domains BH1, BH2, BH3, and BH4, but without the transmembrane region. The VP5 gene from MABV was fused to enhancing green fluorescence protein (eGFP) gene and inserted into the baculovirus genome under the control of polyhedrin gene promoter, and then was highly expressed in insect cells. The expressed VP5 was capable of enhancing insect cell viability, prevented membrane blebbing and delayed DNA internucleosomal cleavage when cells were infected with the recombinant virus. The results suggested that the VP5 of MABV is a novel anti-apoptosis gene, which could regulate the cell apoptosis-off system.

DOI： 10.1007/s11262-005-1794-x

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC LIMNOLOGY OCEANOGRAPHY  

We assayed proteolytic enzymes in coastal surface seawater using 16 types of fluorogenic substrates, including those for aminopeptidase, trypsin, elastase, and chymotrypsin. Hydrolysis rates were similar or higher for substrates of trypsin and chymotrypsin than for those of aminopeptidase. Substrates for elastase were hardly hydrolyzed. The results strongly suggest trypsin-type and chymotrypsin-type endopeptidases and aminopeptidases were present in the seawater. In most previous studies of proteolytic enzymes in aquatic environments, leucine-aminopeptidase activity measured using a fluorogenic substrate has been used as a model of proteolytic activity. From the results of this study using various peptide analog fluorogenic substrates, the significance of endopeptidases, which could play a key role in downsizing of dissolved proteins and polypeptides to oligopeptides prior to microbial respiration, was confirmed.

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING LTD  

A phylogenetic tree of aquabirnaviruses, including marine birnaviruses (MABV) and infectious pancreatic necrosis virus (IPNV), was developed based on the nucleotide sequences and deduced amino acid sequences of the polyprotein and VP5 genes of genomic segment A. In the polyprotein of MABV strains, the amino acid sequences were very similar, with identities of 98.3-99.7%. Twenty-one unique amino acid residues were found in the deduced amino acid sequences of the polyprotein gene of MABV strains. The phylogenetic tree based on the nucleotide sequence of genomic segment A and polyprotein sequences showed that 31 aquabirnavirus strains were clustered into seven genogroups. All MABV strains isolated in Japan and Korea were clustered into one genogroup which was distinct from other aquabirnaviruses. The seventh genogroup containing all MABV strains showed amino acid sequence similarities of 80.7-90.6% with other genogroups. In VP5, four unique residues were found in MABV strains when compared with IPNV strains. The MABV strains exhibited amino acid sequence similarities of 63.9-86.4% with IPNV strains. The amino acid sequences of VP5 were conserved among MABV strains, but differed from those of IPNV strains. The MABV strains isolated from different host species and different geographical areas were very similar to each other, suggesting that the MABV are distinct from the other genogroups.

DOI： 10.1111/j.1365-2761.2004.00585.x

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TERRA SCIENTIFIC PUBL CO  

To examine the possibility that outer membrane proteins (OMP) of Synechococcus sp. remain in seawater, we investigated the stability of OMPs in vitro and in situ. Some fractions prepared from Synechococcus sp. CSIRO-94 were treated with trypsin and proteinase K. Four tightly bound OMPs were separated from Synechococcus. We designated the two major OMPs of 52 kDa and 48 kDa as Omp52Sy and Omp48Sy, respectively. Degradation of the OMP in natural seawater was monitored in microcosms to which intact Synechococcus cells and outer membrane (OM) were added. Omp52Sy and Omp48Sy were the most stable against trypsin and proteinase K among the OMPs when they were embedded in the OM. However, in the microcosm experiment using intact cells, Omp52Sy and Omp48Sy were detected in the particulate fraction only during the first 4 days, after which they could not longer be detected. Omp52Sy and Omp48Sy were the most stable proteins among the Synechococcus OMPs in vitro, but they might be degraded in situ. This indicates that stability of Synechococcus porin differs depending on complex formation with other membrane molecules, which might cause different preservation of microbial membrane proteins in the dissolved protein pool in the ocean. This study suggests that Gram negative bacterial OM with thin peptidoglycan forms a lipid bilayer that proptects OMP, but Synechococcus OM with thick peptidoglycan cannot form a lipid bilayer. The incomplete bilayer might not be able to protect from protease attack in the natural environment.

DOI： 10.1007/s10872-004-5775-9

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Occurrence of tetracycline resistance genes encoding ribosomal protection proteins was examined in 151 tetracycline-resistant bacterial isolates from fish and seawater at coastal aquaculture sites in Japan and Korea. The tet(M) gene was detected in 34 Japanese and Korean isolates, which included Vibrio sp., Lactococcus garvieae, Photobacterium damsela subsp. piscicida, and unidentified Gram-positive bacteria. The majority of these bacterial isolates displayed high-level resistance with a minimum inhibitory concentrations (MICs) equal to or greater than 250 mug/ml of oxytetracycline and only four isolates had MICs less than 31.3 mug/ml. 16S rDNA RFLP typing of tet(M)-positive Vibrio isolates suggests that these are clonal populations of the same phylotype specific to a particular location. One Vibrio clone (phylotype III), however, is widely disseminated, being detected during different sampling years, at different locations, and in different fish species in both Japan and Korea. The tet(S) gene was detected in L. garvieae from yellowtail in Japan and in Vibrio sp. from seawater in Korea. This is the first report of tet(S) occurrence in Gram-negative facultative anaerobes. These results suggest that tet(M) and tet(S) genes are present in fish intestinal and seawater bacteria at aquaculture sites and could be an important reservoir of tetracycline resistance genes in the marine environment. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.femsle.2004.06.026

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INTER-RESEARCH  

We examined the inactivation kinetics of marine birnavirus (MABV) in a coastal sea, in seawater samples collected from 50 cm depth. MABV was added to both natural and autoclaved seawater at a concentration of 6 x 10(6.43) TCID50 (50% tissue culture infectious close) ml(-1), put in dialysis tubes and incubated at the original depth. The inactivation of MABV by solar UV radiation was examined using light and dark tubes. The infectivity titer of MABV was measured by the TCID50 method using CHSE-214 cells. Virus infectivity in natural seawater decreased quickly and was below the detection limit by 270 min in both light and dark conditions; however, virus infectivity was maintained in the autoclaved seawater until 420 min. These results suggest that the loss of virus infectivity is not caused by sunlight UV radiation.

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING LTD  

To determine the distribution of marine birnavirus (MABV) in cultured populations of different marine fish species, 1291 pooled tissue samples from 2672 fish belonging to 22 species and one hybrid were collected from Kagawa Prefecture, Japan, during 1999-2001. Using cell-culture MABV was isolated from three species: yellowtail, Seriola quinqueradiata Temminck & Schlegel (positive number/sample number, 10/419), amberjack, S. dumerili (Risso) (4/72), and Japanese flounder, Paralichthys olivaceus (Temminck & Schlegel) (41/481). Using PCR on MABV-negative samples, the MABV genome was detected in the same three species [yellowtail (9/409), amberjack (4/68) and Japanese flounder (93/440)] and two additional species, spotted halibut, Verasper variegatus (Temminck & Schlegel) (5/11), and goldstriped amberjack, S. lalandi Valenciennes (1/5). These MABV-positive species can be taxonomically divided into two groups: the genus Seriola and flatfish. In Japanese flounder, MABV was detected during all seasons, and the infection rate was correlated with water temperature. Aquaculture sites with MABV-positive fish were evenly distributed over the surveyed area, suggesting that MABV is widely distributed at aquaculture sites in Kagawa Prefecture. The nucleotide sequence at the variable region, the VP2/NS junction, revealed that the 39th base mutation occurs host-specifically for flatfish. Flatfish are suspected to be the main reservoir of MABV and might be responsible for establishing the infection cycle in aquaculture environments.

DOI： 10.1111/j.1365-2761.2003.00518.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00248-003-1032-9

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10126-002-0085-y

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： Miyoshi2003FishPath_Nocardia PCR.pdf

DOI： 10.3147/jsfp.38.93

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00705-002-0951-y

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INTER-RESEARCH  

Marine birnaviruses (MABVs) infect a wide range of fish and shellfish, yet their mode of transmission is still unclear. To determine whether marine plankton serve as a vector for MABVs, we examined plankton collected from the Uwa Sea, Japan. The phytoplankton and zooplankton were collected monthly, at depths of 0 and 40 m, from May to November 2001. Detection of the MABV genome was carried out using 2-step PCR and virus isolation. Viral genome was detected in zooplankton collected at 0 m depth in September and at 40 m depth in November. The virus could not be isolated in the PCR-positive samples. These results suggest that zooplankton may act as a vector of MABVs, although the infective and/or accumulated virus titer in zooplankton was low.

DOI： 10.3354/dao054069

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 03.Concentration of .pdf

DOI： 10.1007/s10126-002-0057-2

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.18.74

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

new oxytetracycline (OTC) resistance (Otc(r)) determinant,, Tet 34, was cloned from chromosomal DNA of Vibrio sp. no. 6 isolated from intestinal contents of cultured yellowtail (Seriola quinqueradiata). The transformant, containing cloned Tet 34, could grow in broth containing 25 jig of drug per nil with 10 mM MgCl2.. Tet 34 encoded an open reading frame (ORF) 154 amino acids long. The amino acid sequence of the ORF was homologous to sequences of several bacterial xanthine-guanine phosphoribosyltransferases (XPRTs), which Mg2+ binding site residues and the active site were highly conserved act in purine nucleotide salvage synthesis. in XTRT and the ORF of Tet 34. The results suggest that Tet 34 encodes a new Mg2+-dependent Ote(r) mechanism.

DOI： 10.1128/AAC.46.5.1550-1552.2002

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.2002.26

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1046/j.1439-0426.2001.00291.x

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 01.Infectivity of .pdf

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3147/jsfp.36.99

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.2001.191

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 01.Formation of viable.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 00.Occurrence of marine birnavirus.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 00.Seasonal change.pdf

DOI： 10.1007/s007050070036

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.2000.189

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.2000.223

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1023/A:1011109329434

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 99.Isolation of different .pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3147/jsfp.34.121

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3147/jsfp.34.73

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japanese Society of Fish Pathology  

DOI： 10.3147/jsfp.34.228

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3147/jsfp.33.275

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2331/fishsci.64.428

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 1998アコヤからビルナ分離.pdf

DOI： 10.2331/fishsci.64.342

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.13.197

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2331/fishsci.63.563

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 97.Effect of haemin.pdf

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 97.Partial purification.pdf

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1264/jsme2.12.125

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 97.Detection of aquatic.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 97.Low-temperature-active.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3354/meps158001

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 96.Antigenecity and N-terminal.pdf

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 96.Genogrouping og birnaviruses.pdf

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3147/jsfp.31.9

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2331/fishsci.62.148

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3147/jsfp.30.209

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：STOCKTON PRESS  

A tributyltin chloride (TBTCl)-resistant bacterium, Alteromonas sp. M-1, was isolated from coastal seawater. This bacterium grew in medium containing 125 mu M TBTCl. TBTCl added to the medium was taken up by this bacterium, however, the amount of TBTCl in the cellular fraction was low after the logarithmic phase, suggesting the existence of a TBTCl-efflux system. A genetic library was constructed using plasmid vector pUC 19. Three positive clones were obtained, by which E. coli was transformed to TBTCl resistance. Of the three clones, the shortest fragment from HindIII-library was analyzed. This fragment was 1.8 kb long and contained one complete open reading frame. The predicted amino acid sequence of this open reading frame had a homologous domain to transglycosylases of bacteriophage and E. coli. TBTCl-tolerant marine bacteria other than Alteromonas sp. M-1 were obtained from natural seawater to which TBTCl was added. DNA-DNA hybridization was performed between the three cloned fragments from Alteromonas sp. M-1 and chromosomal DNA of the TBTCl-tolerant bacteria. Some strains hybridized with the fragments and some did not, suggesting that several genes are responsible for TBTCl tolerance.

添付ファイル： 95.Tributyltin-resistant marine bacteria.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2331/fishsci.60.713

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2331/fishsci.60.741

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 94.Evidence for relatedness.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2331/fishsci.60.353

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/BF00414880

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0928-8244(94)90051-5

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1472-765X.1994.tb00799.x

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 94.Characteristics of porin-like.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 94.The 16S rRNA.pdf

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担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）  

添付ファイル： 94.Purification and characterization.pdf

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添付ファイル： 94.Occurrence of tributyltin.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 94.Characteristics of cytotoxin.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 93.Cloning of gene.pdf

DOI： 10.1006/bbrc.1993.1883

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3147/jsfp.28.91

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

添付ファイル： 93.Characterization of extracellular.pdf

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添付ファイル： 93.Different pathways.pdf

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添付ファイル： 93.Inhibition by agmatine.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 92.Occurrence of tributyltin.pdf

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0378-1097(92)90493-8

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 92.Detection of viral.pdf

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添付ファイル： 92.Acute toxicity.pdf

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添付ファイル： 92.Inhibition of the electron.pdf

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添付ファイル： 91.Inhibition of duck.pdf

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担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）  

添付ファイル： 91.Synergistic inhibitory.pdf

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添付ファイル： 91.Phospholipid and fatty.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1472-765X.1991.tb00518.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/BF01940675

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 90.Partial purification.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 90.Simultaneous determination.pdf

DOI： 10.1016/S0021-9673(00)91259-7

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 89.Different properties.pdf

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1128/AAC.33.3.336

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0378-1097(89)90337-6

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担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）  

添付ファイル： 89.Distribution and .pdf

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 88.Inhibition of duck .pdf

DOI： 10.1016/S0006-291X(88)80752-6

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担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）  

添付ファイル： 88.Profiles of polyamine.pdf

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 87.Inhibitory effects.pdf

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1292/jvms1939.49.403

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 87.A Proposed mechanism.pdf

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0166-3542(87)90023-4

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

添付ファイル： 86.Characterization of DNA.pdf

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）  

添付ファイル： 86.Delay of herpesvirus.pdf

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1128/AAC.28.2.326

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0042-6822(84)90119-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0166-3542(83)90031-1

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0166-3542(83)90030-X

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総ページ数：xxix, 546 p.   記述言語：英語  

CiNii Books

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総ページ数：xv, 261p   記述言語：日本語  

CiNii Books

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総ページ数：xiii, 432p, 図版 [8] p   記述言語：日本語  

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総ページ数：x, 508p   記述言語：日本語  

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総ページ数：xii, 252p   記述言語：日本語  

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総ページ数：ix, 204p, 図版 [8] p   記述言語：日本語  

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総ページ数：冊   記述言語：日本語  

CiNii Books

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総ページ数：viii, 237p   記述言語：日本語  

CiNii Books

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総ページ数：xxvii, 470 p.   記述言語：英語  

CiNii Books

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総ページ数：xvi, 343 p. :ill.   記述言語：英語  

CiNii Books

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総ページ数：282p   記述言語：日本語  

CiNii Books

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総ページ数：xvi, 326 p.   記述言語：英語  

CiNii Books

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総ページ数：xix, 379 p.   記述言語：英語  

CiNii Books

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）  

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 19.Drug resistant bacteria Ocean Newslett Selected.pdf

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 18.海にもいる薬剤耐性菌 Ocean Newslett.pdf

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記述言語：日本語   掲載種別：講演資料等（セミナー，チュートリアル，講習，講義他）  

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

添付ファイル： 臨床微生物（合）2018s.pdf

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

添付ファイル： 17.水環境に拡散する 公衆衛生.pdf

DOI： 10.11477/mf.1401208759

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：動物用抗菌剤研究会  

添付ファイル： 14.水圏環境は薬剤耐性＿動物抗菌薬.pdf

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添付ファイル： 12.水圏環境におけるバイオサイエンスとインダストリ.pdf

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

添付ファイル： 12.魚介類養殖環境における.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）   出版者・発行元：愛媛大学農学部  

添付ファイル： 11.Effect of exposure.pdf

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その他リンク： http://iyokan.lib.ehime-u.ac.jp/dspace/handle/iyokan/1365

記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 10.Aeromonas molluscorum.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 10.Tetracycline resistance.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 10.Abundance of sulfonamide.pdf

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担当区分：最終著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 10.Distribution of mercury.pdf

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担当区分：最終著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 10.The effect of zinc.pdf

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担当区分：責任著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）  

添付ファイル： 09.フミン酸分解菌.pdf

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記述言語：日本語  

J-GLOBAL

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 09.Changes in proteolytic.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 09.Quantitative analysis.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 08.Cell-to-cell.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 08.Occurrence rates of sulfa-.pdf

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

添付ファイル： 08.水環境における薬剤耐性菌.pdf

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添付ファイル： 07.水圏環境における日水誌.pdf

DOI： 10.2331/suisan.73.317

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）   出版者・発行元：愛媛大学  

魚類、アコヤガイ、養殖場、疾病（ウイルス病）、ビルナウイルス、感染、インドネシア。

添付ファイル： 07.Virus detection.pdf

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その他リンク： http://iyokan.lib.ehime-u.ac.jp/dspace/handle/iyokan/1352

記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 07.ナノサイズのウィルス.pdf

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担当区分：最終著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 06.Microbial degradation.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）   出版者・発行元：Universal Academy Press  

添付ファイル： 06.Transfer of tetracycline.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 06.Occurrence of tetracycline.pdf

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記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 06.Tributyltin(TBT)　resistance.pdf

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（大学・研究所紀要）  

添付ファイル： 05.逆浸透膜を.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 05.Tetracycline resistance.pdf

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

添付ファイル： 04.Effect of Tributyltin.pdf

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担当区分：最終著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 03.海洋環境に.pdf

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）  

添付ファイル： 03.十勝沖コア試料中.pdf

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記述言語：日本語   出版者・発行元：地球環境財団  

添付ファイル： 02.海洋における有機スズ化合物.pdf

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記述言語：日本語   出版者・発行元：愛媛大学農学部  

1994年から1999年まで、西日本各地でアコヤガイの大量斃死が続いたが、原因究明の過程で著者らは斃死状態のアコヤガイからMABVを分離した。アコヤガイから分離されたMABV(JPO-96株)は実験感染ではアコヤガイに対する病原性は弱いとされている。しかし、台湾で分離されたビルナウイルスはハマグリにおいて重金属や温度差などのストレス下で強い病原性を示すことが報告されていることから、西日本で起こったアコヤガイ大量斃死の場合も、貝に何らかのストレスが加わりMABVの病原性が増大した可能性がある。また、MABVは病気の魚介類のみならず、様々な健康な魚介類からも分離されており、宿主域が広く環境中にも遍在していることが考えられる。これらの点から、MABVの宿主内および環境中における動態を知ることは魚介類の防疫の面から重要である。しかし、MABVの水圏環境における動態を体系的に検討された報告はない。本稿では、宇和海におけるMABVの生態に関して、得られた知見を紹介する。

添付ファイル： 02.宇和海のアコヤガイと.pdf

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その他リンク： http://agriknowledge.affrc.go.jp/RN/2010660878

担当区分：最終著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 01.宇和海のアコヤガイ漁場.pdf

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 00.海洋細菌のタンパク質.pdf

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）  

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記述言語：日本語   出版者・発行元：文永堂出版  

添付ファイル： 99.魚介類ビルナウイルス.pdf

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 99.ポーリンはなぜ.pdf

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：機関テクニカルレポート，技術報告書，プレプリント等  

添付ファイル： 98.アコヤガイでの通年動態.pdf

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

添付ファイル： 98.Molecular ecology.pdf

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 98.宿主域の広い.pdf

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記述言語：英語   出版者・発行元：高知大学海洋生物教育研究センター  

添付ファイル： 98.Experimental infection.pdf

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担当区分：最終著者,　責任著者   掲載種別：機関テクニカルレポート，技術報告書，プレプリント等  

添付ファイル： 97.海産魚のビルナウイルス.pdf

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

添付ファイル： 97.特集Vibrio.pdf

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

添付ファイル： 97.地球上で最も.pdf

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記述言語：日本語   出版者・発行元：一般社団法人 日本生態学会  

添付ファイル： 97.微生物生態研究への.pdf

DOI： 10.18960/seitai.47.1_89

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