Kinetics and pathway of biodegradation of dibutyl phthalate by Pleurotus ostreatus

Abstract

Dibutyl phthalate (DBP) is a plasticizer, whose presence in the environment as a pollutant has attained a great deal of attention due to its reported association with endocrine system disturbances on animals. Growth parameters, glucose uptake, percentage of removal efficiency (%E) of DBP, biodegradation constant of DBP (k) and half-life of DBP biodegradation (t_1/2) were evaluated for Pleurotus ostreatus grown on media containing glucose and different concentrations of DBP (0, 500 and 1000 mg l^-1). P. ostreatus degraded 99.6 % and 94 % of 500 and 1000 mg of DBP l^-1 after 312 h and 504 h, respectively. The k was 0.0155 h^-1 and 0.0043 h^-1 for 500 and 1000 mg of DBP l^-1, respectively. t_1/2 was 44.7 h and 161 h for 500 and 1000 mg of DBP l^-1, respectively. Intermediate compounds of biodegraded DBP were identified by GC-MS and a DBP biodegradation pathway was proposed using quantum chemical calculation. DBP might be metabolized to benzene and acetyl acetate, the first would be oxidated to muconic acid and the latter would enter into the Krebs cycle. P. ostreatus has the ability to degrade DBP and utilizes it as source of carbon and energy.

Keywords: Basidiomycete; Biodegradation pathway; Constant of biodegradation; Plasticizer; Removal efficiency.