Degradation of dibutyl phthalate and diethyl phthalate by indigenous isolate Bacillus sp. MY156

Abstract

Dibutyl phthalate (DBP) and diethyl phthalate (DEP) are among the most extensively utilized plasticizers and widely exist in the environment causing adverse effect on human health. Previous studies on these phthalic acid esters (PAEs) biodegradation mainly involved individual substrates. However, these contaminants are more possible existed in mixtures. This work explored the biodegradation of DBP and DEP and their interactions using the indigenous isolate Bacillus sp. MY156. The results demonstrate DBP could be completely degraded by strain MY156 with high efficiency, while DEP showed relatively lower removal efficiency (72%) in 120 h. The binary substrate removal results revealed the coexistence of DBP and DEP had no significant influence on the degradation of each under the optimal pH and temperature. Nevertheless, slight retardation of the removal efficiency for DEP noticed as co-existed with DBP demonstrated their removal was possibly affected through the substrate competition. The dehydrogenase activity assay illustrated the behaviors of dehydrogenases caused by long-side chains PAEs were higher than PAEs with shorter alkyl chains. The isolate Bacillus sp. MY156 showed a positive utilization potentiality for bioremediation of PAEs-polluted environment.