Interaction between Zygosaccharomyces bailii and Schizosaccharomyces pombe enhances acetic acid reduction in Baijiu fermentation.

Acetic acid is a crucial organic acid in the production of sauce-flavored Baijiu, influencing microbial succession during fermentation. Nevertheless, excessive concentrations of acetic acid can inhibit the growth and metabolism of microorganisms. Consequently, elucidating the microbial interactions under acidic stress is vital. Our study demonstrates that industrial-scale fortification with a defined four-strain yeast consortium significantly reduces acetic acid by 21.9% at the end of heap fermentation and improves starch utilization efficiency and ethanol yield. By employing a cell-contact-free dual-chamber system, this study reveals a synergistic effect on acetic acid reduction during the co-cultivation of Z. bailii and S. pombe. Comparative transcriptomics shows pronounced gene enrichment in the glyoxylate cycle of Z. bailii. The residual acetic acid content was 48.5% higher in the co-cultures involving an MLS1 gene deletion strain of Z. bailii with S. pombe compared to co-cultures with the wild-type Z. bailii, suggesting that the synergistic reduction in acetic acid is likely mediated through upregulation of the MLS1 gene in Z. bailii. This study elucidates the mechanism by which yeast interactions drive acetic acid reduction, offering potential guidance for optimizing acetic acid utilization.