Fig. 4
The effect of Msr(E) expression on elastase and rhamnolipid production by PAO1 and PA14 under 8 μg/mL of azithromycin (AZM). Elastase production was inhibited in wildtype and vector-carrying strains of PAO1 (a) and PA14 (b) under 8 μg/mL AZM, whereas no inhibition was observed in PAO1/pUCP18::msr(E) or PA14/pUCP18::msr(E) that express Msr(E). Similarly, rhamnolipid production was inhibited in wildtype and vector-carrying strains of PAO1 (c) and PA14 (d) under 8 μg/mL AZM, whereas no inhibition was observed in PAO1/pUCP18::msr(E) or PA14/pUCP18::msr(E). The figure shows relative fluorescence units (RFU) or optical density at 421nm (OD421) of the bacterial culture supernatant normalised to optical density at 600 nm (OD600) of the bacterial culture. The measurements are taken from distinct samples and mean ± standard deviation is shown in the bar charts, with individual measurement for each sample represented by orange circles. Two-tailed Student’s t-test was performed for all the control and treatment groups; n = 3 for elastase production assay (a, b) and n = 5 for rhamnolipid quantification assay (c, d). (**P < 0.01, ****P < 0.0001, ns P > 0.05)
