Biodegradation of an endocrine-disrupting chemical di-n-butyl phthalate ester by Pseudomonas fluorescens B-1

Di-n-butyl phthalate ester (DBP) is known as an endocrine-disrupting chemical. A pure culture capable of using DBP as the sole source of carbon and energy from mangrove sediment was identified as Pseudomonas fluorescens B-1. Microbial degradation of DBP was studied in batch experiments for several environmental factors. The effect of initial DBP concentrations on the degradation was investigated between 2.5 and 10.0 mg l−1, and the results showed that the biodegradation process conformed to the first-order kinetic model. The pH value of the culture medium also played an important role in the biodegradation of DBP, the optimum pH being 7.0. The effects of temperature and oxygen availability on the kinetics of DBP biodegradation were also determined. Degradation of DBP by P. fluorescens B-1 was quantified by reversed-phase high-performance liquid chromatography after solid-phase extraction. Two metabolites of DBP degradation were identified as mono-butyl phthalate and phthalic acid by gas chromatography-mass spectrometry. The results suggest that DBP can be degraded by indigenous microorganisms from the mangrove environment.