Dynamic Analysis Of Flora Of Traditional Fermented Bean Sauce And Screening Of Functional Bacteria

Traditional fermentation soybean paste is one of the four most popular traditional fermented soybean products, along with soybean sauce, sufu and douchi. A variety of microorganisms play an important role in koji incubation and the paste fermentation in traditional method. A series of complicated biochemical reactions occur during the period, providing soybean paste with specific flavor and nutrition. Microorganisms play a significant role in the fermentation progress of traditional fermentation soybean paste. They have heavy correlation to the flavor and the quality of the soybean paste. So the investigation about the species, quantity of the microorganisms and their fermentation properties will be useful to improve the pure-cultured technology and quality of the soybean paste.In the present paper, the samples of soybean paste in Heilongjang province were investigated. Viable count and denaturing gradient gel electrophoresis (DGGE) analysis method of the partially amplified 16S rDNA were applied to obtain a more detailed view of the dynamic of community structure and amount of dominant population during the fermentation of soybean paste. The fungal diversity during the fermentation of soybean paste was investigated by viable count and DGGE analysis of the partially amplified 18S rDNA. My results demonstrate that bacterial communities in soybean paste are much more complex than previously believed. Analyses revealed complex bacterial communities consisting of members and relatives of the genera Aeromonas, Weissella viridescens, Staphylococcus xylosus, Lactobacillus brevis, Aeromonas media, Staphylococcus saprophyticus, Leuconostoc lactis, Uncultured Staphylococcus, Listeria grayi, Bacillus subtilis, Staphylococcus succinu, Bacillus firmus, Uncultured Oceanobacillus, Tetragenococcus Halophilus, and Uncultured Clostridium. Bacillus subtilis and Lactobacillus brevis were the main bacterium responsible for soybean paste fermentation. My results demonstrate that fungal communities consist of members and relatives of the genera Penicillium expansum, Aspergillus oryzae, Mucor, Penicillium commune, Absidia corymbifera, Mucor racemosus, Actinomucor elegans, and Aspergillus. Aspergillus oryzae were the main fungus responsible for soybean paste fermentation. The strain HDF-7 with high protease activity and high amylase activity was isolated. It was identified as Aspergillus oryzae. The salt-tolerant yeast HDY-6 was isolated. It was identified as Zygosaccharomyces rouxii. The salt-tolerant lactic acid bacteria HDL-1 with low lactic acid activity was isolated. It was identified as Pediococcus acidilactici. The strain HDBF-1 with high fibrinolyticenzyme activity was isolated. It was identified as Xanthomonas sp.In the dissertation, the samples of soybean paste in Heilongjang province were investigated, then the strain of soybean paste during different fermentation were separated, cultivated, calculated and identificated. The microflora and the changing principle of the bacteria family at different fermentation stage were studied. DGGE is used in the study of the microbiology analysis as a non-culture method. The strains were screened from nature fermentation soybean paste, thus providing theoretical basis to develop suitable technology of artificial inoculation.