不同时期窖泥理化因子、风味物质和细菌组成的相关性

Characterization and correlation analysis of the bacterial composition,physicochemical properties and volatiles in Baijiu fermentation pit mud of different ages

摘要:

【背景】窖泥品质是影响浓香型白酒质量的重要因素之一，窖泥的理化特性、微生物群落结构和风味物质等与窖泥的品质有关。【目的】揭示不同时空浓香型白酒窖泥理化因子、细菌群落结构和挥发性风味物质三者之间的关系。【方法】比较演替期(10年)和成熟期(30年)的窖泥理化因子，利用顶空固相微萃取-气相色谱质谱联用分析窖泥中挥发性风味物质，采用PacBio SMRT高通量测序分析窖泥细菌组成，通过Spearman相关性分析法分析三者间的相关性。【结果】成熟期窖泥的含水量、有效磷和有效钾及己酸、己酸乙酯、丁酸乙酯等关键风味物质含量均高于演替期窖泥，乳酸和己醇等物质含量则低于演替期窖泥。演替期窖泥中丰度最高的是拟杆菌纲的嗜蛋白菌属(Proteiniphilum)和理研菌属(Petrimonas)，而成熟期窖泥中丰度最高的是梭菌纲的己酸菌属(Caproiciproducens)和梭菌属(Clostridium)。梭菌纲微生物(Caproiciproducens和Clostridium等)与窖泥中己酸和己酸乙酯等风味物质呈正相关，与乳酸呈负相关。窖泥理化特性对关键风味物质和梭菌纲大多数菌属有直接或间接影响，其中窖泥含水量、有效磷和有效钾与梭菌纲菌属呈正相关。【结论】窖泥含水量、有效磷和有效钾含量是影响窖泥中梭菌纲微生物组成和浓香型白酒特征风味物质己酸与己酸乙酯含量的关键因素。这些发现促进了对演替期和成熟期窖泥在菌群结构和风味物质组成演变的理解，有助于促进浓香型白酒发酵调控和窖泥改良。

关键词:窖泥;理化因子;挥发性风味物质;微生物群落;斯皮尔曼相关性

Abstract:

[Background] The quality of pit mud (PM) is one of the critical factors affecting the quality of Luzhou-flavor Baijiu.The physicochemical properties,microbiome,and volatiles determine the quality of PM.[Objective] To reveal the relationship between physicochemical properties,microbiome,and volatiles of PM at different ages.[Methods] The physicochemical properties of growing PM (10 years) and mature PM (30 years) were compared.Volatiles were analyzed by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS).PacBio SMRT high-throughput sequencing was conducted to analyze the microbiome.Spearman’s correlation analysis was performed with the obtained data.[Results] Moisture,available phosphorus and potassium,and the key flavor volatiles (caproic acid,ethyl caproate,and ethyl butyrate) in mature PM were higher than those in growing PM,whereas lactic acid and hexanol showed the opposite trend.Proteiniphilum and Petrimonas(Bacteroidia) were most abundant in growing PM,whereas Caproiciproducens and Clostridium(Clostridia) were most abundant in mature PM.The relative abundance of Clostridia(Caproiciproducens and Clostridium) was positively correlated with the content of caproic acid and ethyl caproate,and negatively correlated with the content of lactic acid.The physicochemical properties of PM influenced most species of Clostridia in PM.Moisture and available phosphorus and potassium were positively correlated with the content of key volatiles and the relative abundance of Clostridia.[Conclusion] Moisture,available phosphorus and potassium are the key factors affecting both the composition of Clostridia and the content of key volatiles (caproic acid and ethyl caproate) in Luzhou-flavor Baijiu.These findings improve our understanding of the microbial succession and volatile profile in PM,which facilitates the fermentation regulation and PM quality improvement of Luzhou-flavor Baijiu.

Key words:pit mud;physicochemical properties;volatiles;microbial community;Spearman correlation