Fig. 5: Lactonases affect the formation of biofilms by supragingival plaque community in vitro under 5% CO₂ atmosphere and their subsequent ability to ferment sucrose to lactate.

Biofilms of supragingival plaque community grown in 5% CO₂ atmosphere in the presence of indicated lactonases [5A8 (inactive lactonase), SsoPox, and GcL; 200 μg/mL] were either A heat dried in a SpeedVac or B resuspended in peptone-buffered water and incubated with 0.2% sucrose under anaerobic conditions for 4 h for lactate production. The biofilm cells were subsequently removed by centrifugation, and lactate was quantified in the cell-free supernatants using Amplite® Colorimetric L-Lactate Assay Kit according to manufacturer’s instructions. A The total mass of the dried biofilm per lactonase treatment is shown. Each bar represents the mean and standard deviation of dry weights of 6 biological replicates of plaque biofilms, shown as individual data points. B The amounts of lactate produced per unit OD_600nm of supragingival plaque biofilms grown with indicated lactonases (absolute amounts shown in Fig. S10) are normalized to the control (5A8) and represented as % of control. Each bar represents the mean and standard deviation of 6 biological replicates of plaque biofilm incubated with sucrose. As each biological replicate was further assayed twice for lactate measurement, each data point represents the mean of two technical replicates. The annotated number at the inside-bottom of each bar represents the mean value. Statistical significance of all treatments compared to the control (5A8) was calculated using unpaired two-tailed t-tests with Welch’s correction and significance values are indicated as - ***p < 0.0005, **p < 0.005 and *p < 0.05.