A study of complete brewing process of Jiang-flavor Baijiu and brewing functions of thermotolerant actinomycetes.

Jiang-flavor Baijiu (liquor) derives its distinctive flavor profile from unique brewing process. However, its complete brewing process and the functions of key microorganisms are poorly understood. This study systematically deciphered the dynamic changes throughout entire brewing process of Jiang-flavor Baijiu, and revealed a stage-dominated microbial succession from the thermotolerant to acid-tolerant communities, accompanied by a gradual simplification of microbial networks with fermentation proceeding. Ethanol, acidity, and reducing sugars were identified as the key physicochemical drivers of microbial succession. Meanwhile, critical flavor compounds including acids, esters, and pyrazines, exhibited distinct temporal accumulation patterns. Solid-state fermentation experiments demonstrated that the thermotolerant actinomycetes Kroppenstedtia eburnea and Streptomyces rochei could independently synthesize characteristic flavor compounds of Jiang-flavor Baijiu. This study provides an insight into the complete brewing process of Jiang-flavor Baijiu as well as brewing functions of thermotolerant actinomycetes and develops a new microbial resource for improving Jiang-flavor Baijiu brewing process.