Prebiotic Konjac Glucomannan Hydrolysate Reduces Streptococcus mutans in Oral Biofilms

Objectives: The objective of this investigation was to test the prebiotic potential of Konjac glucomannan hydrolysate (GMH) to produce a decrease in the number of cariogenic bacteria, such as Streptococcus mutans, while increasing the number of probiotic bacteria such as lactobacilli under different environmental conditions.

Methods: The effect of GMH was tested on the in vitro multi-species, HA disc biofilm model. Biofilms were grown under different conditions and the relative presence of lactobacilli and S. mutans were tested both by conventional plating and also by extracting bacterial genomic DNA and quantifying using qPCR.

Results: Both S. mutans and L. acidophilus were able to metabolize GMH when cultured separately in planktonic culture. However, in the biofilm model, presence of GMH resulted in an increase in lactobacilli and a decrease in S. mutans. The prebiotic effect of GMH was not influenced by the presence of glucose; however, the effect was impeded by the presence of sucrose. We observed a reduction of this effect under anaerobic conditions and in the presence of TCA cycle inhibitor.

Conclusions: Using the in vitro multi-species biofilm model, we have demonstrated that the presence of GMH can reduce the number of cariogenic S. mutans and enhance the number of lactobacilli under aerobic conditions. This effect was also dependent on a functional TCA cycle. Mechanistic understanding of this phenomenon may lead to development of prebiotic for optimizing the oral ecology.