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Novel ecological niche of Cetobacterium somerae , an anaerobic bacterium in the intestinal tracts of freshwater fish
Author(s) -
Tsuchiya C.,
Sakata T.,
Sugita H.
Publication year - 2008
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2007.02258.x
Subject(s) - biology , bacteroides , microbiology and biotechnology , 16s ribosomal rna , bacteria , freshwater fish , phylogenetic tree , biochemistry , genetics , fish <actinopterygii> , gene , fishery
Aims: This study was conducted to clarify the taxonomic status of Bacteroides type A strains with high vitamin B 12 ‐producing ability that is widely distributed in the intestinal tracts of freshwater fish. Methods and Results: Seventeen strains of Bacteroides type A isolated from five fish species were all rod‐shaped and gram‐negative. The strains were positive for esculin hydrolysis, nitrate reduction, resistance to bile, acid phosphatase, and negative for the production of catalase and urease and the susceptibility to vancomycin. The G+C content of DNA from the 17 strains was 29·1–31·9 mol%, and 16S rDNA sequence analysis revealed a close phylogenetic relationship between Bacteroides type A strains and Cetobacterium somerae sharing 99·7–100% sequence similarity. In addition, strains were capable of producing vitamin B 12 at a rate of 1·82–13·98 ng ml −1 in 48 h. Conclusion: Phenotypic and phylogenetic characteristics indicated that all isolates previously classified as Bacteroides type A strains belong to C. someare . Significance and Impact of the Study: This study provided the important finding of novel niche of vancomycin‐resistant bacteria such as C. somerae in the intestinal tract of freshwater fish.