Figure 2. The effect of pstS and phoB deletion on phosphate starvation in P.aeruginosa.

PAO1, ΔpstS, ΔphoB and ΔpstSΔphoB were grown for 24 hours at 37°C on swarming plates containing M9 or phosphate-depleted M9. After 24 hours, bacteria were scraped off the plates and Alkaline Phosphatase activity was measured using p-Nitrophenyl Phosphate as described in Materials and Methods. Results were normalized to each samples’ total protein concentration using Bradford assay. Results shown represent mean+standard deviation of six different experiments. Each experiment was performed in triplicate. Asterisks represent the significant rise in AP activity compared to the WT (p<0.05, student’s t-test).