TRYPSIN-DEPENDENT PRODUCTION OF AN ANTIBACTERIAL SUBSTANCE BY A HUMANPEPTOSTREPTOCOCCUS STRAIN IN GNOTOBIOTIC-RATS AND IN-VITRO

An antibacterial substance appeared within 1 day in feces of gnotobiot ic rats harboring a human intestinal Peptostreptococcus strain. It dis appeared when the rat bile-pancreatic duct was ligatured or when the r ats ingested a trypsin inhibitor. Anaerobic cultures of the Peptostrep tococcus strain in a medium supplemented with trypsin also exhibited a n antibacterial activity, which was also inhibited by the trypsin inhi bitor. In vitro the antibacterial substance from both feces and cultur e medium was active against several gram-positive bacteria, including other Peptostreptococcus spp., potentially pathogenic Clostridium spp. such as C perfringens, C. difficile, C. butyricum, C. septicum, and C . sordellii, Eubacterium spp., Bifidobacterium spp., and Bacillus spp. Whatever the order of inoculation of the strains, a sensitive strain of C. perfringens was eliminated within 1 day from the intestine of ra ts monoassociated with the Peptostreptococcus strain. These findings d emonstrate for the first time that very potent antibacterial substance s can be produced through a mechanism involving intestinal bacteria an d exocrine pancreatic secretions.