Glycine fermentation by promotes virulence and spore formation, and is induced by host cathelicidin.

is a leading cause of antibiotic-associated diarrheal disease. colonization, growth, and toxin production in the intestine is strongly associated with its ability to use amino acids to generate energy, but little is known about the impact of specific amino acids on pathogenesis. The amino acid glycine is enriched in the dysbiotic gut and is suspected to contribute to infection. We hypothesized that the use of glycine as an energy source contributes to colonization of the intestine and pathogenesis of . To test this hypothesis, we deleted the glycine reductase (GR) genes , rendering unable to ferment glycine, and investigated the impact on growth and pathogenesis. Our data show that the pathway promotes growth, toxin production, and sporulation. Glycine fermentation also had a significant impact on toxin production and pathogenesis of in the hamster model of disease. Furthermore, we determined that the locus is regulated by host cathelicidin (LL-37) and the cathelicidin-responsive regulator, ClnR, indicating that the host peptide signals to control glycine catabolism. The induction of glycine fermentation by LL-37 demonstrates a direct link between the host immune response and the bacterial reactions of toxin production and spore formation.