Magnesium-Dependent Promotion of HO Production Increases Ecological Competitiveness of Oral Commensal Streptococci.

The pyruvate oxidase (SpxB)-dependent production of HO is widely distributed among oral commensal streptococci. Several studies confirmed the ability of HO to antagonize susceptible oral bacterial species, including caries-associated as well as several periodontal pathobionts. Here we report a potential mechanism to bolster oral commensal streptococcal HO production by magnesium (Mg) supplementation. Magnesium is a cofactor for SpxB catalytic activity, and supplementation increases the production of HO in vitro. We demonstrate that Mg affects transcription and SpxB abundance in and . The competitiveness of low-passage commensal streptococcal clinical isolates is positively influenced in antagonism assays against . In growth conditions normally selective for , Mg supplementation is able to increase the abundance of in dual-species biofilms. Using an in vivo biophotonic imaging platform, we further demonstrate that dietary Mg supplementation significantly improves oral colonization in mice. In summary, our results support a role for Mg supplementation as a potential prebiotic to promote establishment of oral health-associated commensal streptococci.