Impact of Staphylococcus carnosus DG06 inoculation on microbial and metabolic profiles during Cantonese soy sauce fermentation

The natural fermentation of soy sauce presents challenges in process control and raw material residue, limiting its suitability for modern production. This study utilized absolute quantification techniques to investigate inoculation parameters, fermentation performance, biological perturbation, and flavor regulation mechanisms of Staphylococcus carnosus DG06 in Cantonese soy sauce fermentation (CSSF). Results indicated that inoculating S. carnosus DG06 at 6.7 log CFU/g on day 7 significantly enhanced flavor development, particularly esters, alcohols, and ether compounds, while accelerating amino acid production. Although microbial composition and dynamic trends in traditional fermentation (TF) and inoculated fermentation (5IF7) were similar, 5IF7 significantly increased microbial abundance through synergistic interactions among Staphylococcus with Starmerella and Wickerhamiella . Correlation analysis revealed that these interactions promoted flavor production in CSSF. This study provides fermentation parameters of key functional strains for the application of synthetic microbial consortia in intelligent soy sauce brewing.