Unravelling microbial interactions in a synthetic broad bean paste microbial community

Abstract

The biotic factors governing the assembly and functionality of broad bean paste microbiota remain largely unexplored due to its highly complex fermentation ecosystem. This study constructed a synthetic community comprising Zygosaccharomyces rouxii, Staphylococcus carnosus, Bacillus subtilis, Bacillus amyloliquefaciens, Tetragenococcus halophilus and Weissella confusa, representing key microorganisms involved in broad bean paste fermentation. The generalized Lotka-Volterra (gLV) model revealed that the microbial interaction network among the six species was dominated by pairwise interactions. The abundances of most species in the multi-species communities at 2 and 4 days were accurately predicted using the gLV model, based on pairwise species combinations outcomes. Among pairwise interactions, negative interactions (57 %) were significantly more prevalent than positive interactions (37 %), with the former generally being stronger. Subsequent investigations demonstrated that the tested Z. rouxii inhibited acid accumulation by acid-producing bacteria, while the two strains belonging to the genus Bacillus stimulated lactic acid bacteria growth and lactic acid accumulation. The sequential inoculation strategy, informed by the interaction network, enhanced the synthetic community's bioaugmentation in broad bean paste, significantly improving ester and mellow flavors, reducing unpleasant odors, and increasing volatile flavor substances to 9.43 times that of natural fermentation. Overall, this study revealed the interaction network of six key microorganisms in broad bean paste using the gLV model and guided the application of the synthetic community in its fermentation, significantly enhancing flavor quality.