Revealing the formation mechanism of umami peptides in fermented broad bean paste based on peptidomics and macrogenomics

Umami peptides play important roles in the flavor of fermented broad bean paste (FBBP), and proteases produced by microorganisms contributed to the production of umami peptides. In order to reveal the formation of umami peptides and their relationships with protease-producing microorganisms during the natural fermentation of FBBP, peptidomics and virtual screening were used to identify and screen umami peptides. Meanwhile, macrogenomics was used to analyze the abundance of microbial-derived protease genes during FBBP fermentation. Then, based on the Pearson correlation coefficient, the correlation network diagram of each protease-producing microorganism with umami peptides was constructed. The results showed that a total of two exopeptidases and four endopeptidases were annotated from FBBP. <i>Staphylococcus</i>, <i>Lactobacillus</i>, <i>Aspergillus</i>, and <i>Weissella</i> can produce most proteases. The species <i>Lactobacillus curvatus</i>, <i>Dyella jiangningensis</i>, <i>Erythrobacter</i> sp., and unclassified_g_<i>Pantoea</i> had strong correlation with umami peptides, and they may contribute to the process of protein hydrolysis to produce umami peptides. This study is expected to reveal the formation mechanism of umami peptides in FBBP, and the results of this study provided a better understanding of the relationship between proteases, microbiota, and core umami peptides in FBBP, which could help to improve the umami taste of Pixian Douban paste during fermentation.