Temperature-driven functional microbial interactions in soy sauce fermentation: Effects of Zygosaccharomyces rouxii and Wickerhamiella versatilis on flavor enrichment and biogenic amine reduction

This study elucidates the temperature-dependent interactions between halotolerant yeasts and microbial communities during secondary fortified soy sauce fermentation (SFFSS) and their implications for flavor enhancement and safety. A dual-mode fermentation system compared natural temperature fermentation (NTF) and controlled temperature fermentation (CTF, 30 °C), each with and without co-inoculation of Zygosaccharomyces rouxii and Wickerhamiella versatilis (ZC). Multi-omics analyses integrating amplicon sequencing, metagenomics, and metabolomics revealed that CTF control elevated amino acid nitrogen and aroma compounds, while increasing biogenic amines (BA) by 47.88 %. In both NTF and CTF modes, the ZC pattern significantly reduced lactic acid while enhancing succinic acid, umami/sweet free amino acids, and key aroma compounds (e.g., 4-ethylguaiacol, 5-ethyl-4-hydroxy-2-methyl-3(2H)-furanone), alongside enriching functional bacteria ( Staphylococcus , Weissella ), stabilizing fungal communities, and suppressing Tetragenococcus and Ligilactobacillus pobuzihii . Mechanistically, ZC pattern promoted tricarboxylic acid cycle flux and amino acid metabolism, synergistically enhancing volatile phenolics, esters, and alcohols, and reduced BA by >87 % via dual modulation of decarboxylase inhibition and oxidase activation. Network analyses linked microbial composition shifts to targeted flavor metabolite synthesis, providing a mechanistic framework for microbial community engineering. These findings highlight yeast-mediated, temperature-driven modulation of microbiota–metabolite networks as a viable strategy for producing high-quality, safe soy sauce with optimized flavor complexity.