泸型酒酒醅细菌群落的发酵演替规律

Bacterial community succession in fermented grains of Luzhou-flavor baijiu

摘要:

[目的]考察泸型酒发酵过程中酒醅细菌群落的演替规律，探讨菌群演替与环境因素变化的相关性。[方法]采用高通量测序技术分析泸型酒酒醅细菌群落的演替规律，并运用Mantel test分析不同发酵阶段的细菌群落演替与环境因素变化的相关性。[结果]酒醅发酵过程中有397个属的微生物，其中Lactobacillus、Bacillus、Weissella、Dysgonomonas、Comamonas以及Ruminococcaceae为优势属（相对丰度>1.0%）。通过聚类分析可将酒醅发酵过程划分为3个阶段：阶段I（0-5 d），阶段Ⅱ（6-17 d）和阶段Ⅲ（18-40 d），且3个阶段的酒醅菌群结构差异显著（P<0.05）。Metastats分析结果表明，与阶段I相比，阶段Ⅱ酒醅细菌群落中Lactobacillus和unclassified Lactobacillaceae相对丰度显著升高（P<0.05），而unclassified Bacillaceae、Staphylococcus、Bacillus、unclassified Enterobacteriaceae、Lactococcus、Pseudomonas、Thermoactinomyces、Leuconostoc、Staphylococcus相对丰度显著降低（P<0.05）。与阶段Ⅱ相比，阶段Ⅲ酒醅细菌群落中Lactobacillus相对丰度显著增长（P<0.05），Comamonas、Acetobacter、unclassified Bacilli、Clostridium、Bacillus、Ruminococcus、unclassified Porphyromonadaceae和unclassified Streptophyta相对丰度显著下降（P<0.05）。结果表明，阶段I的细菌菌群演替与酒醅温度、水分和乙醇浓度变化线性相关（P<0.05）；阶段Ⅱ和阶段Ⅲ的细菌菌群演替与酒醅温度、水分、酸度、乙醇浓度均没有相关性（P>0.05）。[结论]泸型酒酒醅中细菌群落在不同发酵阶段结构差异显著，且温度、水分以及乙醇浓度对酒醅发酵前期（0-5 d）细菌群落演替具有重要作用。

Abstract:

[Objective] This study aimed to elucidate the bacterial community succession and its underlying relevance to the environmental factors in fermented grains of Luzhou-flavor baijiu. [Methods] The 16S rRNA gene amplicon sequencing analysis was applied to reveal the succession of bacterial community in the fermented grains, and Mantel test was used to correlate bacterial community succession with environmental factors. [Results] A total of 397 bacterial genera were identified in fermented grains, including Lactobacillus, Bacillus, Weissella, Dysgonomonas, Comamonas and Ruminococcaceae (relative abundance>1.0%). Fermentation process was divided into three stages:stage I (0-5 d), stage Ⅱ (6-17 d) and stage Ⅲ (18-40 d) according to clustering analysis, and the bacterial community structure was significantly different among these three stages. Metastats analysis demonstrated that the relative abundance of Lactobacillus and unclassified Lactobacillales in stage Ⅱ was significantly higher than that in stage I (P<0.05), whereas the situation of unclassified Bacillaceae, Staphylococcus, Bacillus, unclassified Enterobacteriaceae, Lactococcus, Pseudomonas, Thermoactinomyces, Leuconostoc and Staphylococcus quite the reverse (P<0.05). Compared with stage Ⅱ, the relative abundance of Lactobacillus increased in stage Ⅲ (P<0.05), conversely, downregulation dominated Comamonas, Acetobacter, unclassified Bacilli, Clostridium, Bacillus, Ruminococcus, unclassified Porphyromonadaceae and unclassified Streptophyta (P<0.05). Results of Mantel test indicated that the bacterial community succession in the stage I was correlated with the dynamics of temperature, moisture, and alcohol concentration (P<0.05), whereas no significant correlation was observed between environmental factors and bacterial community succession in the stage Ⅱ and Ⅲ (P>0.05). [Conclusion] Our work demonstrated the dramatically divergent bacterial community structure in the fermented grains of Luzhou-flavor baijiu from different brewing stages. Temperature, moisture and alcohol concentration significantly correlated with the bacterial community succession in early stage of fermentation (0-5 d).