Metagenomics and volatile metabolomics reveal microbial succession and flavor formation mechanisms during fermentation of Novel Pasture-style Laozao.

Novel Pasture-style Laozao (NPLZ) is a local specialty fermented food with unique flavor and mouthfeel. This study investigated the dynamic changes of physicochemical properties, volatile flavor substances and microbial community succession during the fermentation of NPLZ and revealed their interactions through the joint analysis of metagenomics and volatile metabolomics. Differences in the contents of 52 characteristic flavor substances were the main reasons for the changes in aroma. Saccharomyces cerevisiae, Pseudomonas oryzihabitans, and Pantoea vagans were the dominant microbial communities during fermentation. Under symbiotic conditions, five species including Paenibacillus piri and Methyloversatilis thermotolerans were found to be crucial in influencing microbial community succession. The accumulation of organic acids was identified as the primary environmental factor driving changes in microbial community structure. Through correlation analysis, eight microbial species were identified as core microorganisms affecting flavor differences, and the metabolic networks of key flavor metabolites were reconstructed in conjunction with the KEGG database.