传统清香型白酒发酵过程中细菌群落演替及自组装机理

Bacterial Community Succession and Self-assembly Mechanism during the Fermentation Process of Traditional Light-flavor Baijiu

基于PacBio SMRT测序技术对传统清香型白酒发酵过程中细菌物种组成和群落结构开展研究,进一步利用iCAMP模型探究发酵过程中细菌群落自组装机制。结果表明,在发酵过程中细菌多样性随发酵过程呈现先降低后升高趋势,其中乳杆菌属(Lactobacillus)、醋酸菌属(Acetobacter)、片球菌属(Pediococcus)和魏斯氏菌属(Weissella)等为优势属,桥乳杆菌(L. pontis)、类消化乳杆菌(L. paralimentarius)、短乳杆菌(Lactobacillus brevis)和耐酸乳杆菌(L. acetotolerans)等为优势种。根据不同发酵时间细菌群落间差异,可将整个发酵过程分为阶段Ⅰ(0 d)、阶段Ⅱ(3~10 d)和阶段Ⅲ(12~28 d)。其中,苹果醋杆菌(A. malorum)、L. paralimentarius和L. pontis分别是阶段Ⅰ、Ⅱ和Ⅲ的差异菌种,且不同阶段差异菌种之间呈显著负相关,同一发酵阶段差异菌种之间呈显著正相关。此外,替换是细菌群落变化的主要过程,随机性过程中的漂移是驱动细菌群落自组装的最重要过程。同时,淀粉含量、温度和水分含量可能是发酵过程中细菌群落自组装的主要影响因素。以上结果深入揭示传统清香型白酒发酵过程中细菌物种组成,群落演替规律及自组装机制,可为调节清香型白酒发酵过程中微生物群落及进一步优化多种微生物在混合发酵过程中的作用提供基础理论。

In this study,we investigated the bacterial community composition and structure during the fermentation process of traditional light-flavor baijiu using PacBio SMRT sequencing technology,and further explored the mechanism of bacterial community self-assembly during the fermentation process using a framework to quantitatively infer community assembly mechanisms by phylogenetic bin-based null model analysis(iCAMP).The results showed that the bacterial diversity decreased and then increased during the fermentation process.Lactobacillus,Acetobacter,Pediococcus and Weissella were identified as the dominant genera,and L.pontis,L.paralimentarius,L.brevis and L.acetotolerans as the dominant species.According to the differences among bacterial communities at different fermentation times,the whole fermentation process could be divided into three stages:I(0 days),II(3–10 days)and III(12–28 days).Acetobacter malorum,L.paralimentarius and L.pontis were the differential species in stages I,II and III,respectively,and there were a significant negative correlation between the differential species in different stages and a significant positive correlation between the differential species in the same fermentation stage.In addition,turnover was the major process responsible for bacterial community changes,and drift during stoichiometry was the most important process driving bacterial community self-assembly.Meanwhile,starch content,temperature and moisture content may be the main factors influencing bacterial community self-assembly during fermentation.The above results provide insight into the bacterial species composition,community succession patterns and self-assembly mechanisms during the fermentation of traditional light-flavor baijiu,which can provide a theoretical basis for regulating the microbial communities in the baijiu brewing process and further optimizing the role of multiple microorganisms in the mixed fermentation process.