浓香型酒醅中活性梭菌群落多样性及其与挥发性有机酸代谢的关联性

Community Diversity of Active Class of Clostridia in Fermented Grains for Production of Chinese Strong Flavor Baijiu and Its Correlation with Volatile Organic Acid Metabolism

为探索浓香型白酒发酵酒醅中具有转录活性的梭菌群落及其与挥发性有机酸代谢的相关性,采用宏转录组学技术和气相色谱-质谱法对酒醅中活性梭菌群落的组成、演替、功能以及挥发性有机酸种类进行了分析。结果表明:梭菌群落由6个目、27个科及148个属组成,其中包含1个优势菌科Heliobacteriaceae;梭菌群落的平均相对丰度在发酵15 d时达到最高,其变化规律可将酒醅发酵分为前期(3~7 d)、中期(7~25 d)和后期(25~60 d)3个阶段。相对含量从高到低排名前10的属与乙酸、丁酸和己酸等8种挥发性有机酸呈现不同程度的相关性。KEGG功能注释表明供试酒醅中梭菌主要参与碳水化合物代谢、翻译和能量代谢等过程,其中来自12种可鉴定属及不可鉴定的属的25个基因和22种碳水化合物酶参与到乙酸和丁酸的合成途径中,其相关基因在发酵45 d时具有最大的表达量,其中Clostridium(梭菌属)是主要的贡献菌。研究旨在进一步阐明浓香型酒醅复杂微生态体系中活性梭菌群落的组成和功能,为揭示浓香型白酒固态酿造机理提供基础数据和理论支撑。

In order to investigate the correlation between the transcriptionally active Clostridia and the volatile organic acids metabolism in the fermented grains for the production of Chinese strong flavor Baijiu(CSFB),the methods of macrotranscriptomics and gas chromatography-mass spectrometry were used to determine the composition,succession,function of active Clostridia,and types of organic acids in fermented grains of CSFB.The results showed that there were 6 orders,27 families,148 genera assigned into Clostridia detected,and Heliobacteriaceae was dominat bacteria at the family level.The average relative abundance of clostridial community reached highest level at 15th day for the fermentation.The whole fermentation process could be divided into three phases according to the abundance variation of clostridial community,early fermentation(3-7 d),middle fermentation(7-25 d),and late fermentation(25-60 d).Various degrees of correlations had been observed between the top 10 genera and eight volatile organic acids,such as acetic acid,butyric acid,caproic acid and etc..The KEGG functional annotation indicated that Clostridia was mainly involved in carbohydrate metabolism,translation,and energy metabolism.The synthesis pathway of acetic acid and butyric acid involved 25 genes and 22 carbohydrate enzymes from 12 identifiable genera and unidentified genera,and their related genes had the highest expression level at 45th day for the fermentation,with Clostridium was the main contributor.This study aimed to provide basic data and theoretical support for further revealing the solid-state brewing mechanism of CSFB,and help clarify the composition and function of active clostridial communities in the complex microecosystem of fermented grains for the production of CSFB.