A Synthetic Microbial Community Enhances Flavor and Safety in Reduced-Salt Soy Sauce Fermentation: Multi-Omics Insights into Microbial Stabilization and Metabolic Regulation

Reducing sodium in soy sauce fermentation while preserving flavor and safety presents significant technical challenges. To address this, we constructed a synthetic microbial community (SynMC) comprising Tetragenococcus halophilus T10, Zygosaccharomyces rouxii QH-25, and Wickerhamiella versatilis CGMCC 3790 for reduced-salt fermentation (13%NaCl). Multi-omics analysis revealed three coordinated improvements: First, microbial community stabilization through suppression of spoilage taxa (e.g., Millerozyma ) and enrichment of functional genera (e.g., Wickerhamiella ), reducing negative ecological correlations from 5.3% to 1.7% compared to the low-salinity control group. Second, metabolic restructuring enhanced characteristic aromas while reducing biogenic amines (BAs) to 21.98 mg/L (76% lower than L group). Third, metatranscriptomics identified upregulated amino acid metabolism (238% more BA-degrading enzymes) and carbohydrate utilization pathways. These synergistic effects indicate that strategic microbial consortia design can overcome the salt reduction challenge through targeted ecological and metabolic regulation, enabling industrial-scale production of superior, safer low-salt soy sauce.