Exploring the capacity of Bacillus species for production of kokumi γ-glutamyl peptides: A comparative study

gamma-Glutamyl peptides are an important class of kokumi compounds that enhance the palatability of food. To investigate the ability of Bacillus species to produce gamma-glutamyl peptides, strains of B. subtilis, , B. safensis, , B. velezensis, , B. altitudinis and B. paralicheniformis, , were isolated from the fermented seed condiment "Kantong" and cultured in the dark in a conventional medium for 5 days. Quantitation of gamma-glutamyl peptides was performed alongside analyses of bacterial growth and gamma-glutamyltransferase (GGT) activity. Results showed that all strains could produce a variety of gamma-glutamyl peptides. Compared to the other strains, strains of B. subtilis and B. safensis demonstrated greater capacities to generate target gamma-glutamyl peptides, achieving maximum concentrations of 2.02 and 1.77 mg/L, respectively. Moreover, no direct correlation between GGT activity and gamma-glutamyl peptide concentrations was observed during fermentation, and these two indicators were reported for the first time for B. safensis and B. paralicheniformis. . This study provides valuable insights into the generation of gamma-glutamyl peptides through Bacillus fermentation, facilitating the development of cost-effective and environmentally friendly approaches for producing kokumi seasonings.