FIG 5.
Use of the phoZ reporter to determine a concentration-dependent response to p-HPA for induction of the hpdBCA operon. (A) Expression from PhpdB-phoZ was monitored in MM with increasing concentrations of p-HPA (0.5, 1, 1.5, and 2 mg/ml). (B) Expression from PhpdB-phoZ was tested with p-HPA concentrations of 0.1, 0.25, and 0.5 mg/ml. The expression of the phoZ reporters was quantified by using the following formula: [OD420 – (OD550 × 1.75)] × 1,000/t (min) × OD590 × volume of cells (ml). Statistical analysis was performed. (A) Linear regression was used to determine any effect on phosphatase activity as p-HPA concentration increases (R2 = 0.8429, P < 0.001); (B) linear regression was used to determine at what p-HPA concentration there was a significant effect on expression compared to the absence of p-HPA (*, P < 0.05; **, P < 0.01).