Environment-Specific Probiotic Supernatants Modify the Metabolic Activity and Survival of .

A range of studies showed probiotics like and to inhibit the cariogenic activity and survival of , possibly via the production of substances like HO, reuterin, ammonia and organic acids. We aimed to assess the environment-specific mechanisms underlying this inhibition. We cultured and in various environments; minimal medium (MM), MM containing glucose (MM+Glu), glycerol (MM+Gly), lactic acid (MM+Lac), arginine (MM+Arg) and all four substances (MM+all) . Culture supernatants were obtained and metabolite concentrations (reuterin, ammonia, HO, lactate) measured. was similarly cultivated in the above six different MM variation media, with glucose being additionally added to the MM+Gly, MM+Lac, and MM+Arg group, with (test groups) and without (control groups) the addition of the supernatants of the described probiotic cultures. Lactate production by was measured and its survival (as colony-forming-units/mL) assessed. environment-specifically produced reuterin, HO, ammonia and lactate, as did . When cultured in supernatants, lactate production by was significantly reduced ( < 0.01), especially in MM+Lac+Glu and MM+all, with no detectable lactate production at all (controls means ± SD: 4.46 ± 0.41 mM and 6.00 ± 0.29 mM, respectively, < 0.001). A similar reduction in lactate production was found when was cultured in supernatants ( < 0.05) for all groups except MM+Lac+Glu. Survival of cultured in supernatants in MM+Lac+Glu and MM+all was significantly reduced by 0.6-log and 0.5-log, respectively. Treatment with the supernatant of resulted in a reduction in the viability of in MM+Gly+Glu and MM+all by 6.1-log and 7.1-log, respectively. Probiotic effects on the metabolic activity and survival of were environment-specific through different pathways.