Biodegradation of omethoate by Bacillus sp. YB-10: optimization of culture conditions and degradation characteristics

Abstract

Omethoate is an acute organophosphorus pesticide which is widely used. It presents a high pollution potential and health risk nowadays. In this study, Bacillus sp. YB-10, which was isolated from the activated sludge of a pharmaceutical wastewater treatment plant, was used for degrading omethoate. The culture conditions and degradation characteristics were investigated. Results showed that the Bacillus sp. YB-10 could degrade omethoate through co-metabolism. The optimal carbon and nitrogen sources were glucose and NH4NO3, respectively. Response surface methodology (RSM) results showed that the most appropriate nutrition ratio of C:N:P was 3:1:1 when degrading 1,000 mg/L of omethoate. Omethoate degradation kinetics could be described by a first-order rate equation. The optimal degradation conditions were pH of 7.0, temperature of 30℃, initial bacteria concentration of 0.25%, rotation speed of 150 r/min. Under the optimal conditions, the degradation rate reached 77.24% within 5 d by the Bacillus sp. YB-10 when the initial omethoate concentration was 1,000 mg/L.