A strain of Streptococcus mitis inhibits biofilm formation of caries pathogens via abundant hydrogen peroxide production
Our group recently transcriptomically characterized coculture growth between Streptococcus mutans and several species of commensal streptococci (Rose et al, 2023; Choi et al 2024). One interaction that stood out was with Streptococcus mitis ATCC 49456, which completely inhibited the growth of S. mutans during biofilm formation. This is due to abudant hydrogen peroxide production by S. mitis ATCC 49456, 3-5x higher than other oral commensal streptococci we have worked with. To understand how the transcriptome of S. mutans is modified in coculture with a high hydrogen peroxide producer, we evaluated the transcriptome during monoculture or coculture growth between the two strains. Our results show differential gene expression (DEGs) in S. mutans that follows other trends we have documented previously with other commensal Streptococcus species, as well as DEGs specific to the interaction with S. mitis. Overall design: Streptococcus mutans UA159 and Streptococcus mitis ATCC49456 were grown either as monocultures or cocultures, inoculated 1:1. All samples were grown in TYG. Cultures were harvested during mid exponential growth phase (OD600 nm = 0.4). Resulting comparisions included differentially expressed genes (DEGs) between monoculture and coculture growth for each strain.