Figure 5

lasI and rhlI gene promoter activities and quantitative determination of 3-oxo-C12-HSL. a) lasI gene promoter activities measured via β-galactosidase assay in PUPa3 in different stages of growth. The white colorless bars represents the control culture P. aeruginosa PUPa3 with the vector pMP220; light grey represents P. aeruginosa PUPa3 harboring pLASI; dark grey, represents P. aeruginosa PUPa3 harboring pLASI with addition of SIC of tobramycin (0.05 μg/mL). b) rhlI gene promoter activities measured via β-galactosidase assay in PUPa3 in different stages of growth. The white colorless bars represents the control culture P. aeruginosa PUPa3 with the vector pMP220; light grey represents P. aeruginosa PUPa3 harboring pRHLI; dark grey, represents P. aeruginosa PUPa3 harboring pRHLI with addition of SIC of tobramycin (0.05 μg/mL). The β-galactosidase activities were performed at different stages of growth: assay 1 was performed during log phase, assay 2 during early stationary phase, assay 3 and assay 4 during stationary phase. Each assay was performed in biological triplicates. Error bars represent the standard deviations calculated from at least three separate experiments.