Bioactive metabolite profiling in mixed-species probiotic yogurt

Yogurt consumption is a natural way of accessing bioactive metabolites such as peptides and short-chain fatty acids (SCFA). Proteolytic systems and metabolic pathways of lactic acid bacteria (LAB) and probiotics, which differ among the species, influence bioactive metabolite profiles in yogurt. This study determined the bioactive peptide and SCFA profiles in mixed-species yogurt incorporating Bifidobacterium bifidum ATCC 11863, Bifidobacterium breve ATCC 15700, Bifidobacterium animalis ssp. animalis ATCC 25527, and Lacticaseibacillus rhamnosus GG using ultra-performance liquid chromatography coupled to electrospray ionization quadrupole-time-of-flight MS and GC-MS, respectively. Significantly higher proteolytic activities were observed in yogurt incorporating either probiotic species of B. bifidum ATCC 11863 or L. rhamnosus GG. Yogurt incorporating B. bifidum ATCC 11863 contained more peptides with higher bioactivity. Bifidobacterium animalis ssp. animalis ATCC 25527 significantly enhanced the SCFA content (acetic acid) in yogurt. Whereas L. rhamnosus GG increased the production of both bioactive peptides and SCFA in yogurt when incorporated as a monoculture or coculture with B. bifidum ATCC 11863 and B. animalis ssp. animalis ATCC 25527, respectively. Novel short peptides (<10 AA) derived from minor milk serum proteins with potential antimicrobial properties were identified in the different probiotic yogurts. This study provides insights into the bioactive metabolite profiles of yogurt incorporating probiotics, L. rhamnosus and Bifidobacterium spp., and their role in developing yogurt with enhanced therapeutic benefits.