Isolation and identification of psychrotrophic lactic acid bacteria in godo , the traditional fermented soy food in Japan

[摘要] Godo is a traditional fermented soy food made inAomori prefecture, Japan. It is mainly made of soybeans, rice koji, and salt. Since godo ripens duringthe long and severe winter in northeast Japan, it isassumed that lactic acid bacteria inhabiting godohave cold tolerance. We aimed to investigate thepresence or absence of psychrotrophic lactic acidbacteria in godo. The viable counts of estimatedlactic acid bacteria ranged from 106 to 108 cfu/g. Inaddition, aerobic and anaerobic microorganismswere detected in four godo products though themicrobial population differed from sample to sample. Twenty-two bacterial strains were able to beisolated from godo, and all of the isolated strainswere Gram-positive and catalase-negative. Some ofthe isolates grew well at 10°C. The carbohydratefermentation profile of the selected three strains wasdetermined by API50 CHL analysis. These strainswere identified as Leuconostoc mesenteroides, andLatilactobacillus sakei by 16S rRNA gene sequenceanalysis. Leuconostoc mesenteroides strains HIT231and HIT252, and Latilactobacillus sakei strainHIT273 could grow at 5°C in MRS broth, but theiroptimum growth temperature was 20°C-30°C. Theseresults suggest that psychrotrophic lactic acid bacteria presumed to be derived from rice koji are present in godo, which is one of the factors in thelow-temperature ripening of godo in winter.

[学科分类] 微生物学和免疫学

[关键词] fermented soy foods;godo;lactic acidbacteria;psychrotroph