关键词: 冬尖, 聚合酶链式反应-变性梯度凝胶电泳, 细菌多样性

Abstract: Objective: To investigate dynamic changes in the microbial community structure during the fermentation of Zizhong Dongjian, a Chinese traditional fermented vegetable product, by polymerase chain reaction-denatured gradient gel electrophoresis (PCR-DGGE). Methods: Four samples of Dongjian with different fermentation times were collected from Zizhong, Sichuan province. Total bacterial DNA was extracted from the samples, and nested PCR was applied to amplify the V3 region of 16S rDNA for identification based on DGGE fingerprints. Meanwhile, the dominant bands were cloned, selected and sequenced, and a phylogenetic tree was constructed. Results: During the fermentation process of Dongjian, rich bacterial diversity was observed and the microbial community structure was changed greatly. The similarity of bacterial community between Dongjian samples with different fermentation times ranged from 9% to 67%. Among them, samples fermented for two and three years exhibited the highest similarity to each other, up to 67%. Furthermore, the bacteria involved in the fermentation process of Dongjian were mainly divided into 3 categories: Firmicutes, Proteobacteria, and unculturable bacteria. Among these, Firmicutes was the most dominant species followed by Proteobacteria, which accounted for 53% and 37% of the total population, respectively, while unculturable bacteria accounted for only 10%. Conclusions: DGGE fingerprint can provide a comprehensive and true reflection of dynamic changes in the microbial diversity of Dongjian during fermentation. Meanwhile, it also provides a theoretical basis for the production process for Dongjian and the formation of flavor substances.

Key words: Dongjian, polymerase chain reaction-denatured gradient gel electrophoresis, bacterial diversity