The Microbial Community Structure Of Traditional Pickled Vegetables Studied By PCR-DGGE

Fermented vegetable, as an important processing mode, is a kind of traditional food invovled complicated microorganiam. We not only can gain the information of dominant groups, but also obtain a scientific basis for strains filtration and industaial peoduction by using PCR-DGGE technology to study microbial diversity.In this paper, twenty homemade pickle samples and seven pickled vegetables were collected from diverse families and factories(four Dongcai samples collected from Nanchong, three Yacai samples from Yibin.) respectively in Sichuan region. Extract total DNA as a template before amplify16S rDNA V3area of bacteria and ITS region of fungi. Then, PCR products were analyzed by degeneration gradient gel electrophoresis (DGGE). The microbial community structure of fermentated vegetables in Sichuan region were studied by the statistical analysis on DGGE atlas and construct phylogeny tree.DGGE fingerprint of homemade pickle showed that there were a certain degree of difference in electrophoresis strip number, strength and the mobility, which indicated the diversity of bacteria and fungi. The brightness of strip in each lane revealed biomass and the number of strip directly reflected genetic diversity of the community. Bacteria were abundant, while fungi were relatively few in homemade pickle. Twenty five sequences of bacterial and ten sequences of fungi were successful sequenced after cloning and sequencing. The similarity of all bacteria sequences were between98%and100%compared with16S rDNA sequences in the database. Lactobacillus and uncultured bacteria were the dominant bacteria. In addition, there were Pediococcus and Lactococcus with small proportion. What’s more, Pseudomonas was existed in certain samples. The similarity of ten fungi sequences were all above97%. Meyerozyma guilliermondii was the dominant species, which existed in almost all samples. Moreover, Kodamaea ohmeri, Debaryomyces hansenii, Aspergillus, Candida tropicalis and uncultured fungi existed in vary samples.It is the first time to study microbial diversity of Yibin Yacai and Nanchong Dongcai by PCR-DGGE technology. The dominant bacterial flora in the two kinds of pickled vegetables were Lactobacillus, which acounted for50%and54%respectively. Twelve bacterial sequences were successfully sequenced, including six Lactobacillus, five uncultured bacteria in three Yacai samples. Lactobacillus played a dominant role in Yacai fermention. Thirteen bacterial sequences were obtained in four Dongcai samples including seven Lactobacillus (made up54%), and five uncultured bacteria. The same groups were existed in two kinds of samples, which demonstrated the microbe were similar which played an important role in both fermented vegetables. Pseudomonas were found in individual samples. Eight fungi sequences were achieved, contained six uncultured fungi and two Debaryomyces hansenii. Uncultured fungi played an important role in both Yacai and Dongcai fermentation. The microbial diversity in Yacai samples with sugar was significantly lower than the other. Microbial community was more diversity in liquid samples than in solid samples, while microbial diversity in the samples of three-month-fermentation was significantly more rich than that in samples of three-year-fermentation.In summary, PCR-DGGE technology can truly reflrct the abundant microbial community structure in three types of fermented vegetables, and bacterial species were much more than fungi. The main flora identified from three types of fermented vegetables can guide the separation of good strains and lay the foundation for industrialization of fermented vegetables.