Fig. 2

A Growth curves of ΔmltG type (indicated with blue line) and wild type (indicated with grey line) strains of S. mutans. B Survival rate of ΔmltG type with respect to the wild-type has been shown with bar-graph, a significant (p < 0.001) reduction in survival of ΔmltG S. mutans was also estimated as 68.2 ± 4.5%. C Glycolytic curve. Effect of deletion of mltG gene on acidogenicity of S. mutans. Glycolytic acid production was determined by monitoring the pH decrease in glucose solution (1% v/v) over a period of 6 h. Wild-type represented with grey line and ΔmltG type with blue line. D Effect of deletion of mltG gene on aciduricity of S. mutans. Acid tolerance was determined by measuring the survival rate of S. mutans at different pH values such as 2.8, 5.0, and 7.0 on Todd Hewitt agar plates incubated for 48 h at 37˚C. Wild-type represented with grey line and ΔmltG type with blue line. Number of colonies survived expressed in cfu/mL. E Biofilm formation by ΔmltG type (represented with blue bar) and wild-type (represented with grey bar) strains of S. mutans quantified by crystal violet staining. Results are expressed as means ± standard deviations of triplicate assays from two independent experiments. Image inserts show SEM analysis of of biofilm formed by wild and ΔmltG type strains of S. mutans. Scale bar = 10 μm. F Quantitative real time qRT-PCR analysis of specific genes to figure out differentially expressed genes in ΔmltG type. Housekeeping gene 16S rRNA were used for normalization. The expression level of the wild-type is set to one for each gene. Significantly up regulated than wild-type (P < 0.05). Significantly down regulated than wild-type (P < 0.05). The assays were performed in triplicate and the means ± SD from three independent experiments were calculated