What Bioactive Peptides and Metabolites Do Bifidobacterium and Lactobacillus Probiotics Actually Produce?

The researchers grew 14 different probiotic strains (from Bifidobacterium and Lactobacillus families) and collected their cell-free supernatants — essentially the liquid left after removing the bacteria. They then used untargeted metabolomics to identify and compare all the small molecules, peptides, and other metabolites produced by each strain, using principal component analysis to map the differences.

Postbiotics — the beneficial substances produced by probiotic bacteria — are gaining attention as a way to deliver health benefits without requiring live bacteria. This study provides the first detailed metabolic fingerprint comparing what Bifidobacterium and Lactobacillus actually produce, revealing that the peptide and amino acid profiles differ substantially between these two major probiotic families. Understanding these differences could help researchers design more targeted probiotic or postbiotic therapies.

The postbiotics field is rapidly growing as researchers recognize that many probiotic health benefits come not from the bacteria themselves but from the peptides and metabolites they produce. This study provides a foundational metabolic map that could guide the development of next-generation postbiotic supplements targeting specific health outcomes based on their peptide composition.

This was an in vitro laboratory analysis — the metabolites were identified in culture conditions, not in the human gut. Whether these same peptides and metabolites are produced in meaningful amounts inside the body remains unknown. The study also did not test the biological activity of the identified peptides, only their presence.