Fig. 6: Lactonase treatment alters the utilization of carbon sources by supragingival plaque community biofilms (pre-grown in vitro under 5% CO₂ atmosphere with lactonases) on Biolog EcoPlates™.

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 washed, resuspended in peptone-buffered water at an OD_600nm of 0.2, and incubated in Biolog EcoPlates under 5% CO₂ atmosphere at 37°C for 24–48 h. The time course absorbance was recorded (OD₅₉₀ and OD₇₅₀) and the Area-Under-the-Curve (Abs_AUC) or endpoint values (OD_590-750) determined, representing metabolic utilization of carbon sources, as explained in the Methods section. The mean Abs_AUC values of 3 replicates were normalized to the control (5A8) and represented as % carbon source utilization compared to control (5A8). Differences were observed for utilization of Tween-20 [A 5A8 vs Sso; C 5A8 vs GcL] and Tween-80 [B 5A8 vs Sso; D 5A8 vs GcL] by the plaque biofilms. SsoPox W263I (Sso) treated plaque biofilms (2 replicates) metabolized N-acetyl-D-Glucosamine (NAG) while 5A8 treated plaque biofilms (3 replicates) did not, as represented by mean and standard deviation of endpoint (OD_570-750) reads at 24 h (E) and 48 h (F). One biofilm replicate (out of 3) grown with SsoPox that failed to metabolize NAG was deemed an outlier and excluded from analysis. 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 and significance values are indicated as - ***p < 0.0005, **p < 0.005 and *p < 0.05.