Fig. 3
Synonymous point mutant strain gtfB 2043 T>C decreased the EPS production and biofilm formation. a The biofilms formation of WT, #858, gtfB 2043 T>C and ΔgtfB based on the crystal violet assay. Each values is mean ± SD (n = 6). b Crystal violet staining of biofilms. c Growth curves of S. mutans strains. The OD600 values were recorded at 1 h interval during the 20-h cell growth period at temperature of 37 °C (n = 6). d The SEM images of biofilms under 1000 × , 5000 × and 20,000 × magnified visual field. e The 3-dimensional reconstruction of biofilms (bacteria, stained green; EPS, stained red). f The volume of EPS and bacteria, calculated according to 3 random sights of controlled biofilms (n = 3). g The quantitative data of the water-insoluble polysaccharide amount from four S. mutans strains, measured by anthrone method at 625 nm (n = 3). h The expression of EPS synthesis related genes of S. mutans (n = 3). i Coomassie blue staining of Gtfs from culture supernatants of S. mutans variants, in which GtfB and GtfD co-migrate together and are separated from the band of GtfC. Culture supernatnants were prepared and analyzed by 6% SDS-PAGE. J, The quantification of fluorescent intensity of Gtfs from S. mutans strains. Data are presented as mean ± standard deviation. (* p < 0.05, ** p < 0.01, *** p < 0.001)