Synergistic modulation of flavor profiles in slightly fermented bonito by synthetic microbial communities: Insights from integrated proteomics and untargeted metabolomics.

Abstract

The aim of this study was to investigate the molecular mechanisms by which synthetic microbial communities (SynComs) modulate flavor formation in fermented bonito using an integrated approach based on proteomic and untargeted metabolomic analyses. The results showed that SynCom inoculation effectively shifted the microbial framework from a stochastic background state toward a more structured community, with Kluyveromyces marxianus identified as a key contributor to enhanced fungal diversity. Multi-omic results revealed that the Staphylococcus carnosus and Lactiplantibacillus plantarum established an umami foundation through nucleotide metabolism and primary proteolysis. The addition of Bacillus coagulans enriched pathways related to inositol phosphate metabolism and arginine biosynthesis, which was associated with modulation of proteolytic intensity and a more balanced accumulation of umami-related amino acids, potentially contributing to improved fermentation performance. Concurrently, Kluyveromyces marxianus primarily influenced aroma development by enhancing the expression of flavor-conversion enzymes and upregulating the category "phenylalanine metabolism", leading to the enrichment of volatile aromatic compounds. Furthermore, the AMPK and calcium signaling pathways were significantly enriched, suggesting a possible association with cellular energy-related regulatory processes during fermentation. This interspecific metabolic complementarity enhanced sensory quality, resulting in stronger umami intensity and a multi-layered aromatic profile that included unique markers such as 2,7-octadien-1-ol and 2,5-heptanedione. These findings provide theoretical guidance for the precise regulation of fermented seafood quality using designed SynComs.