Studies On Microbial Biodiversity In Traditional Fermented Soybean Processing

Traditional fermented soybean foods have been consumed for more than 1,500 years in China. They were highly digestible and nutritious traditional food condiments. Soybean food fermentations are generally conducted as traditional, indigenous processes in which various types of microorganisms participate. Different microorganisms have different function in fermentation processes. At present, the Chinese fermented soybean food industry was backward. We used the molecular biology technology to analyze the diversity of the Chinese traditional fermented soybean foods. And some important strains were isolated from the samples. The study of communities in Chinese traditional fermented soybean foods could be applied in the local fermented soybean food industry.The present study investigated microbiology communities in Chinese traditional fermented soybean foods using 16S rDNA and 5.8S-ITS-rDNA gene library. The results showed Bacillus and Weissella were the dominant bacteria in fermented soybean food samples. There are Staphylococcus, Enterobacter, Citrobacter, Pantoea, Acinetobacter and Kurthia were found in samples The non-Saccharomyces yeasts were the dominant yeasts species in the Chinese traditional fermented soybean foods. And the dominant molds were Rhizopus oryzae and Aspergillus oryzae. In addition, based on the results of the culture-independent, the optimized culture conditions were selected to isolate yeast strains. 38 strains in 20 different yeast species, belonging to 11 genera were isolated based on their ITS-rDNA sequences in total 15 samples. In addition, two new yeast species not represented in NCBI nucleotide database were found and tentatively were classified as Candida sp. and Blastobotrys sp.76.3% (29/38) and 92.1% (34/38) yeast strains showed lipolytic and proteolytic activity respectively suggesting that different yeasts species could play an important role in the development of fermented soybean foods.