郫县豆瓣细菌多样性及群落结构动态变化

【目的】通过检测郫县豆瓣在不同发酵阶段细菌的种类、丰度及数量,探究郫县豆瓣的不同发酵产品发酵过程中细菌的动态变化情况。【方法】采用16S rRNA基因测序对郫县豆瓣4个发酵阶段中细菌种类及丰度进行分析,利用荧光定量PCR(quantitative real-time PCR,qPCR)方法检测不同发酵阶段的细菌总数。【结果】郫县豆瓣在初期的发酵过程中细菌群落处于动态稳定,在不同发酵阶段细菌群落组成相对丰富,从郫县豆瓣整个初期的发酵过程来看,细菌群落多样性呈现升高的趋势,Shannon指数从1.25升高到3.50;在郫县豆瓣初期发酵过程中细菌群落的数量以及多样性与发酵环境息息相关,不同发酵阶段细菌群落的多样性也有所不同,其中在干辣椒发酵阶段中泛菌属(Pantoea)为最优势菌属,占比为20%;在蚕豆瓣发酵阶段中葡萄球菌属(Staphylococcus)的相对丰度最高,占比为38%;混合发酵后,在红油豆瓣发酵阶段的最优势菌属是乳酸杆菌属(Lactobacillus),占比达到27%,郫县豆瓣发酵阶段的最优势菌属是乳酸杆菌属(Lactobacillus),占比为62%。【结论】推断在郫县豆瓣不同发酵阶段初期相对丰度较大的菌属对郫县豆瓣的质量以及产量可能会产生重大影响。

Diversity and dynamics of bacteria in Pixian broad-bean paste

[Objective] The dynamic changes of bacteria in the fermentation process of Pixian broad-bean paste were explored from the species, abundance, and number of bacteria. [Methods] The 16S rRNA gene sequencing was carried out to analyze the bacterial species and abundance at four fermentation stages of Pixian broad-bean paste, and qPCR was employed to determine the total number of bacteria at different fermentation stages. [Results] The bacteria in Pixian broad-bean paste showed a dynamically stable community at the initial fermentation process, high richness during the whole fermentation period, and increased diversity over fermentation time (Shannon index increased from 1.25 to 3.50). The number and diversity of bacteria were associated with the fermentation environment at the early fermentation stage, and the bacterial diversity varied at different fermentation stages. Pantoea was the dominant genus during the fermentation of dry pepper, accounting for 20%. During the fermentation of broad bean, Staphylococcus had the highest relative abundance, which reached 38%. The dominant genus was Lactobacillus at the fermentation stages of red oil broad bean and Pixian broad-bean paste, with the relative abundance of 27% and 62%, respectively. [Conclusion] The relatively abundant bacteria at the early fermentation stage might have a significant impact on the quality and yield of Pixian broad-bean paste.