The composition, interaction network, and source of microbial community in Shanxi mature vinegar produced by liquid-solid fermentation

Abstract:

[Background] Traditional Shanxi mature vinegar is produced by solid-state fermentation with multiple strains in an open environment. Revealing the composition, interaction network, and source of microbial community facilitates the understanding and regulation of the vinegar fermentation process. [Objective] To reveal the composition, succession, interaction network, and source of microbial community in Shanxi mature vinegar during the fermentation process. [Methods] High-throughput DNA sequencing was performed to reveal the composition, succession, and diversity of the microbial community. SPSS was employed to calculate the Spearman correlation coefficient between species and Gephi was used for the visual analysis of the microbial interaction network. Fast expectation-maximization microbial source tracking (FEAST) was employed to analyze the origin of the microorganisms. [Results] Six bacterial genera and five fungal genera (average relative abundance greater than 1%) were dominant in the fermentation process of Shanxi mature vinegar. The average relative abundance of Acetobacter, Lactobacillus, and Saccharomycopsis were 20.76%, 30.38%, and 46.24%, respectively. The relative abundance of Acetobacter increased gradually during acetic acid fermentation, while the opposite trend was observed for Lactobacillus. The microbial community interaction network showed that Weissella, Lactococcus, Meyerozyma, Loigolactobacillus, Schleiferilactobacillus, and Geobacter had high connectivity (≥7). In addition, Acetobacter demonstrated significant antagonism with Weissella, Schleiferilactobacillus, Loigolactobacillus, Lactococcus, and Meyerozyma. The results of source tracking showed that 1.02% of bacteria and 77.04% of fungi were derived from Daqu on the second day of saccharification. On the first day of acetic acid fermentation, 0.93% of bacteria and 52.82% of fungi were derived from fermented grains. [Conclusion] This study provided important theoretical data for understanding the composition, succession, and interaction network of microbial community and tracking the source of microorganisms during the fermentation process of Shanxi mature vinegar.