Co-metabolic degradation of naphthalene and pyrene by acclimated strain and competitive inhibition kinetics

Abstract

A dominant strain named Ochrobactrum sp. was isolated from soils contaminated with coal tar. The batch experiments were carried out to study the co-metabolic degradation of pyrene by Ochrobactrum MB-2 with naphthalene as the main substrate and the effects of several significant parameters such as naphthalene concentration, pH and temperature on removal efficiency were explored. The results showed that Ochrobactrum MB-2 effectively degraded naphthalene and that the addition of naphthalene favored the degradation of pyrene. The maximum elimination efficiency of naphthalene (10 mg L−1) and pyrene (1 mg L−1) was achieved at pH 7 and 25 °C, and the corresponding values were 99 and 41%, respectively. A competitive inhibition model based on the Michaelis–Menten equation was used to characterize the inhibitory effect of pyrene on naphthalene degradation. The values of the half-saturation coefficient for naphthalene (KS) and dissociation constant of enzyme-inhibitor complex (KC) were determined to be 4.93 and 1.38 mg L−1, respectively.