Impact of the presence of salicylate or glucose on enzyme activity and phenanthrene degradation by Pseudomonas mendocina

Abstract

The effects of addition of salicylate or glucose on enzyme activity and phenanthrene degradation by a new phenanthrene-degrading strain Pseudomonas mendocina were investigated. The phenanthrene degradation rate during the linear-decrease stage changed slightly with addition of salicylate or glucose. For intermediate metabolites, high level accumulation of 1-hydroxy-2-naphthoic acid (1H2N) and slight accumulation of 7,8-benzocoumarin were observed. Compared to the control (with only phenanthrene), the apparent accumulation rate of 1H2N increased in the presence of glucose or of a low concentration of salicylate. Dynamic profiles of activities of two key enzymes, polycyclic aromatic hydrocarbon dioxygenase (PDO) and catechol 2,3-dioxygenase (C23O), were also demonstrated. Salicylate addition led to a higher phenanthrene loading of PDO and a higher C23O activity, while glucose supplementation decreased the activities of PDO and C23O. Based on the kinetic data of phenanthrene degradation and PDO activity, PDO activity may not necessarily be the dominant factor affecting the biodegradation in the presence of salicylate or glucose.