Analysis Of Microbial Community Structures And Metagenome From Traditional Fermented Soybeans In Yunnan

Fermented foods play a substantial role in human diet, which makes it important to investigate the microbial community structures and metabolisms, so as to exploit the resource of microorganism, improve and control the quality of fermented food, and upgrade the function of health care. In this research, we will analyze the microbial community structure of the fermented foods using molecular methods and high-throughout sequencing, then analyze their metagenomes. First, we will dig into the microbial community structures of one type of Yunnan specific traditional fermented food:fermented soybean.We will analyze the bacterial and fungal community structures of fermented soybean from different producing area or in different ferment phases. And the factors that may influence the microbial community structures will also be investigated. The samples were collected from different prefectures and counties of Yunnan province, which were extracted DNA and then carried out PCR amplification with barcoded primer and pyrosequencing. The results indicated that, on the level of phylum, the microbial communities of all the samples were similar. About 80-90% sequences belonged to Firmicutes, while about 10-20% sequences belonged to Proteobacteria. On the level of genus, the microbial communities of the samples from different prefectures and counties existed large differences. The genus of Bacillus, Lactobacillus, Tetragenococcus and Enteric_Bacteria_cluster were all detected in all Prefecture and Counties. Among them, the samples of Dehong Perfecture exhibited good microbial communities structure, in which 46% sequences belonged to Lactobacillus and 26% sequences belonged to Tetragenococcus. Both of the genera were recognized as probiotics and played an important role in the process of fermentation. In the samples of Xishuangbanna Prefecture, the most abandunce sequences belonged to Weissella, which was also recognized as probiotics regular presence in the fermented foods. In addition, Bacillus (18%) and the probiotics of Tetragenococcus (9%), Lactobacillus (8%), Enterococcus (4%) and Leuconostoc (4%) were also detected in the samples of Xishuangbanna Prefecture. In the samples of Dali Prefecture,25% sequences were identified as Staphylococcus and 30% sequences were identified as Bacillus, while the sequences belonging to lactic acid bacteria were very little. The existence of Staphylococcus implied that the samples of Dali Prefecture may have potential safety hazard, which need to make further study. The samples of Puer and Honghe Prefecture were more, of which microbial community structures were complex, so they did not have obvious predominant flora. From the above results, there is a certain relationship between microbial community structure and geographical environment. Based on this, representative samples (the samples of 1D and 2D from Dehong Prefecture) will be taken for metagenomic analysis. The results indicated that the microbial community structure of the two samples were very different. The predominant floras of 1D were Providencia stuartii and Providencia rettgeri, and there existed Enterobacter cloacae (15%) and Escherichia coli (2%).The predominant floras of 2D were Bacillus subtilis and Bacillus amyloliquefaciens. In 1D and 2D,40,644 and 35,459 contigs were obtained with 51.4 Mb and 33.5Mb, of which average length was 1,264 bp and 944 bp and GC-content was 41.93% and 43.08%, respectively. Their stitching rate of these contigs was 80.2% and 91.8%. In 1D and 2D,80,514 and 60,410 genes were obtained. Among them, the number of gene matching to seed database were 65,302 and 50,298. Most of the genes belonged to category of clustering-based subsystems, followed by category of carbohydrate. In additon, there were a part of genes belonging to category of vitamins, prosthetic groups and pigments. Based on above results, we will investigate the metabolic pathway of fermented soybean, reconstruct the genome of main microbes in them, which established the theoretical and experimental foundation forthe efficient detection of the microbiological functions.