Uncovering the microbial community dynamics and metabolic pathways of primary organic acids in Sichuan Baoning vinegar through metagenomics

Sichuan Baoning vinegar, a renowned traditional vinegar in China, exhibits a higher lactic acid content compared to acetic acid. The microbiota plays a crucial role in shaping the unique flavor of vinegar, but the species-level succession of key microorganisms and metabolic pathways of major organic acids in this vinegar are still unclear. This study utilized metagenomic sequencing to elucidate microbial succession during fermentation and the functional roles of the microbial community, as well as explore the metabolic network of lactic acid and acetic acid. Our findings revealed that bacteria dominated the fermentation process, with Acetilactobacillus jinshanensis, Lactobacillus amylovorus, and Limosilactobacillus sp. emerging as the top three species. Notably, Acetilactobacillus jinshanensis, Limosilactobacillus sp., Lactobacillus amylovorus, and Limosilactobacillus pontis were key players in lactic acid production, while acetic acid synthesis might be primarily driven by Lactobacillus amylovorus, Limosilactobacillus sp., Lactobacillus acetotolerans, and Acetobacter pasteurianus. This study enhances our understanding of the key microorganisms and organic acids metabolism in vinegar, shedding light on the fermentation mechanism of cereal vinegar.