Environment-Specific Probiotic Supernatants Modify the Metabolic Activity and Survival of Streptococcus mutans in vitro

Abstract

A range of studies showed probiotics like Streptococcus oligofermentans and Limosilactobacillus reuteri to inhibit the cariogenic activity and survival of Streptococcus mutans, possibly via the production of substances like H 2 O 2 , reuterin, ammonia and organic acids. We aimed to assess the environment-specific mechanisms underlying this inhibition. We cultured L. reuteri and S. oligofermentans 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) in vitro. Culture supernatants were obtained and metabolite concentrations (reuterin, ammonia, H 2 O 2 , lactate) measured. S. mutans 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 S. mutans was measured and its survival (as colony-forming-units/mL) assessed. L. reuteri environment-specifically produced reuterin, H 2 O 2 , ammonia and lactate, as did S. oligofermentans. When cultured in S. oligofermentans supernatants, lactate production by S. mutans was significantly reduced (p < 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, p < 0.001). A similar reduction in lactate production was found when S. mutans was cultured in L. reuteri supernatants (p < 0.05) for all groups except MM+Lac+Glu. Survival of S. mutans cultured in S. oligofermentans supernatants in MM+Lac+Glu and MM+all was significantly reduced by 0.6-log 10 and 0.5-log 10 , respectively. Treatment with the supernatant of L. reuteri resulted in a reduction in the viability of S. mutans in MM+Gly+Glu and MM+all by 6.1-log 10 and 7.1-log 10 , respectively. Probiotic effects on the metabolic activity and survival of S. mutans were environment-specific through different pathways.

Probiotic Effects on Multispecies Biofilm Composition, Architecture, and Caries Activity In Vitro

“…In contrast, any indirect actions of probiotics that have been mediated by supernatant, e.g., bacteriocins (such as reuterin), are likely to play a minor role in the observed microbial communities. This seems to conflict with our previous study, which described reuterin in the supernatant as a promising antimicrobial factor [ 36 ]. However, our previous study only assessed S. mutans monospecies biofilms.…”

Glycerol strengthens probiotic effect of Limosilactobacillus reuteri in oral biofilms: A synergistic synbiotic approach

“…Yu et al. (2020) observed an inhibitory effect of glycerol combined with LATCC on S. mutans that was not observed in the current study. Like A. actinomycetemcomitans , streptococcal species are also more adapted to the oxidative stress and thus naturally more resistant to reuterin.…”

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

“…Probiotics are an effective therapeutic agent for dental diseases, and several interesting aticles were published in 2020 on this topic. [484][485][486][487][488] Probiotics are live microorganisms that, once administered in appropriate quantities, confer health benefits on the host. Probiotics may also be used as alternative or adjuvant therapeutic agents for numerous diseases.…”