Microbial diversity in Kusaya Gravy
Satomi, M.; Kimura, B.; Takahashi, G.; Fujii, T.
Fisheries Science 63(6): 1019-1023
ISSN/ISBN: 0919-9268 Accession: 009019628
Microbial population in kusaya gravy from Niijima Island was analyzed by grouping of functional characteristics and genetic identification from 16S rRNA genes (16S rDNA). Viable conunts in TSSY medium supplemented with 0.1% thioglycolate and 0.3% agar using the MPN method were determined as 1011/ml, which was the highest value compared with previous reports on kusaya gravy. Each of denitrifying, nitrate reducers, sulfate reducers and proteolytic bacteria were estimated as about 109/ml, and starch hydrolyzing and lactic acid producing bacteria were estimated as less than 103/ml. Viable counts on TSA medium, which were superior to BPG and B6P6G media, were 108 CFU/ml. The 16S rDNA were amplified from kusaya gravy by PCR without cultivation of baceria, cloned, and sequenced. Sequence analysis of the cloned partial 16S rDNA indicated that the major bacteria in kusaya gravy were Bacteroides-Cytophaga group bacteria, wall-less spirochaeta-like bacteria, unidentified bacteria, and so on. The results of genetic identification did not coincide with those of cultural methods; i.e., most of the above bacteria have not been isolated by plate methods so far, and Corynebacterium and Peptococcuceae which were representative organisms in the plate surface method under aerobic or anaerobic conditions, respectively, were not detected by the PCR method. These results indicated that there are diverse organisms which are unknown and unculturable in kusaya gravy.