Multi-omics analyses of the mechanism for the formation of soy sauce-like and soybean flavor in Bacillus subtilis BJ3-2

Although soy sauce-like flavor and soybean flavor are two key contributors to the flavor of fermented foods, the key compounds of soy sauce-like flavor and soybean flavor and production mechanisms are still poorly understood and need further investigation. In the present study, we found that the Bacillus subtilis (B. subtilis) BJ3-2 strain has various metabolic properties at different temperatures, and the strain cultured at 37celcius increased the soybean flavor (a special flavor of ammonia-containing smelly distinct from natto) compared with culturing at 45celcius and 53celcius. Interestingly, the strain cultured at 45celcius and 53celcius had a higher soy sauce-like flavor than that in 37celcius. Moreover, a comparative transcriptome analysis of the strain cultured at 37celcius, 45celcius, and 53celcius showed transcriptional changes related to secondary metabolites and ABC transporters, which is critical for the amino acid transport and metabolism in B. subtilis. Meanwhile, proteomics and metabolomics profiling showed a marked change in amino acids transport and metabolism. In addition, the metabolic analysis revealed a significant metabolic difference (including sulfur metabolism, glutathione metabolism, nicotinate and nicotinamide metabolism, cysteine and methionine metabolism, and pyrimidine metabolism) in the strain cultured at 45celcius and 53celcius compared to 37celcius. To sum, this study used the multi-omics profiling tool to investigate the fermentative strains B. subtilis BJ3-2, thus providing a deeper insight into the mechanism of the formation of soy sauce-like flavor and soybean flavor compounds.

Automated summary

This study investigated the mechanism of the formation of soy sauce-like flavor and soybean flavor compounds by using multi-omics profiling tools to analyze the fermentative strain B. subtilis BJ3-2.