Kinetics and mechanisms of p-nitrophenol biodegradation by Pseudomonas aeruginosa HS-D38

The kinetics and mechanisms of p-nitrophenol (PNP) biodegradation by Pseudomonas aeruginosa HS-D38 were investigated. PNP could be used by HS-D38 strain as the sole carbon, nitrogen and energy sources, and PNP was mineralized at the maximum lconcentration of 500 mg/L within 24 h in an mineral salt medium (MSM). The analytical results indicated that the biodegradation of PNP fit the first order kinetics model. The rate constant k(PNP) is 2.039 x 10(-2)/h in MSM medium, KPNP+N is 3.603 x 10(-2)/h with the addition of ammonium chloride and KPNP+C is 9.74 x 10(-3) /h with additional glucose. The addition of ammonium chloride increased the degradation of PNP. On the contrary, the addition of glucose inhibited and delayed the biodegradation of PNP Chemical analysis results by thin-layer chromatography (TLC), UV-Vis spectroscopy and gas chromatography (GC) techniques suggested that PNP was converted to hydroquinone (HQ) and further degraded via 1,2,4-benzenetriol (1,2,4-BT) pathway.