Fig. 1: AHLs are detected in the spent supernatants of a supragingival plaque community cultured in vitro under 5% CO2 atmosphere.
Cell-free culture supernatants of 6 biological replicates of plaque community cultures treated with lactonases 5A8 (inactive lactonase mutant), SsoPox, or GcL were incubated with E. coli AHL biosensor strain JM109 pJBA132. The resulting GFP fluorescence is indicated as relative fluorescence units (RFU) per unit OD600nm of biosensor cultures on the left Y-axis. The equivalent C6-HSL concentration for the corresponding RFU/OD600 values as shown on the right Y-axis was extrapolated from the standard curve of the biosensor response against C6-HSL in Fig. S3 and is only represented as an indication, since the used biosensor is broad spectrum and the reading may be a reflection of many different produced AHLs. Results represent the mean and standard deviation of 6 biological replicate cultures for each lactonase treatment. As each of the cell-free supernatants of 6 biological replicate cultures of the plaque community for all lactonase treatments was further incubated with 6 biological replicates of biosensor cultures, each data point on this graph represents the mean of the 6 biosensor replicates. 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.
