Amylase from Streptococcus pyogenes inhibits biofilm formation in Streptococcus salivarius

Biofilms are extracellular constituents composed of polysaccharides and other substances necessary for bacteria to defend themselves against foreign enemies. Amylase of Streptococcus pyogenes is an enzyme that degrades polysaccharides and other substances and produces nutrients for invasion of epithelial cells. S. salivarius is an oral commensal bacterium that shows antibacterial activity against S. pyogenes. We investigated the relationship between S. pyogenes and S. salivarius to determine whether the amylase of S. pyogenes affects the biofilm of S. salivarius. The amyA gene-deficient strains were generated from S. pyogenes 1529 and MDYK strains, and the amylase production ability of the wild-type and gene-deficient strains were compared. Amylase production in mutant strain was significantly reduced compared to the wild-type strain. Next, the biofilm-forming ability of S. pyogenes was compared between wild-type and mutant strains, and significantly increased biofilm-forming ability was observed in the gene-deficient strains. Next, S. salivarius was cultured to create biofilms, and then wild-type and mutant strains of S. pyogenes were added to the culture. Significantly, the biofilms of S. salivarius with the gene-deficient strains were higher than those with the wild strains. As the biofilm-forming ability of S. salivarius co-cultured with S. pyogenes was compared, the biofilm-forming ability of S. salivarius co-cultured with the mutant strain of S. pyogenes was also significantly increased. These results were common findings for the 1529 and MDYK strains of S. pyogenes. Our results suggest that amylase from S. pyogenes inhibits biofilm formation in S. salivarius.