Multi-omics study of sulfur metabolism affecting functional microbial community succession during aerobic solid-state fermentation

Microbial-mediated sulfur metabolism is closely related to carbon and nitrogen metabolism in natural biological systems. In this study, the effects of sulfur metabolism on microbial communities and functional enzyme succession were investigated based on integrated multi-omics by adding sulfur-containing compounds to aerobic fermentation systems. Sulfur powder was oxidized to S2O32- and subsequently to SO42- by the microbial sulfur-oxidizing system, which lowered the pH to 7.5 on day 7. The decrease in pH resulted in Planifilum (secreted S8, M17 and M32 proteases) losing its competitive advantage, whereas Novibacillus (secreted M14 and M19 metalloproteases) became dominant. Structural proteomics indicated that the surface of Novibacillus proteases has more negatively charged amino acid residues that help maintain protein stability at low pH. These findings aid understanding of the effects of sulfur metabolism on fermentation and the mechanism of microbial adaptation after pH reduction, providing new perspectives on the optimization of fermentation processes.