Staphylococcus sp. XK3H5 Isolated from Pu’er Tea Inhibits Streptococcus Mutans Biofilm Formation by Inhibiting Sucrose Metabolismz,2

Streptococcus mutans (S. mutans) is a keystone pathogen in dental caries pathogenesis, with biofilm formation primarily dependent on sucrose-derived glucans. Pu’er tea, a fermented tea originating from Yunnan Province, China, harbors diverse microbial communities. In the study, Staphylococcus sp. XK3H5 isolated from Pu’er tea showed strong antagonistic activity against S. mutans UA159. Strain XK3H5 exhibited probiotic potential including lysozyme resistance, superior auto-aggregation and co-aggregation capacity with S. mutans, hydroxyapatite adhesion capacity and significant inhibition of S. mutans biofilm biomass. Safety assessment confirmed that Staphylococcus sp. XK3H5 is a non-hemolytic strain, with an inability to produce biogenic amine and susceptibility to six clinical antibiotics. Cell-free supernatant (CFS) of Staphylococcus sp. XK3H5 suppressed S. mutans biofilm biomass. Mechanistic analysis indicated that strain XK3H5 CFS significantly impaired sucrose metabolism in S. mutans, reducing water-insoluble exopolysaccharide production. Notably, qPCR analysis demonstrated that the expression of gtfB, gtfC, gtfD, and ftf genes was down-regulated in S. mutans treated with XK3H5 CFS, which is critical for glucan-mediated biofilm maturation and bacterial adhesion. Our study demonstrated Staphylococcus sp. XK3H5 can inhibit S. mutans biofilm formation, offering an alternative way as a potential oral probiotic.