FIG 4 .

3OHC₈-HSL production and expression from the btaI3 promoter in the wild-type and QS mutant strains of B. thailandensis E264. (A) The biosynthesis of 3OHC₈-HSL was quantified using LC-MS/MS at various times during growth in cultures of the wild-type and ΔbtaR1, ΔbtaR2, and ΔbtaR3 mutant strains of B. thailandensis E264. The error bars represent the standard deviations of the averages for three replicates. (B) The luciferase activity of the chromosomal btaI3-lux transcriptional fusion was monitored in cultures of the wild-type and ΔbtaR1, ΔbtaR2, ΔbtaR3, ΔbtaI1, ΔbtaI2, and ΔbtaI3 mutant strains of B. thailandensis E264. The luminescence is expressed in relative light units per optical density of the culture (RLU/OD₆₀₀).