Isolation and characterization of five chlorpyrifos degrading bacteria

Abstract

Several strains of bacteria were successfully isolated from effluent storage pools of factories producing pesticides and from soil moisture around them. The isolates were capable of utilizing chlorpyrifos (Cp) as the sole source of carbon, phosphorus and energy. Isolates were identified based on16SrRNA sequence analysis and were named IRLM.1, IRLM.2, IRLM.3, IRLM.4, and IRLM.5. IRLM.1 was able to grow at concentrations of chlorpyrifos up to 2000 mg/L and was selected as a preferable isolate for further analysis. The amount of the degraded Cp and the amount of metabolite 3,5,6-trichloropyridinol (TCP) produced were assessed in IRLM.1 by using high performance liquid chromatography (HPLC) techniques. Additionally, the location of the chlorpyrifos-degrading enzyme was determined by comparing the activity of intact bacteria to cytoplasm activity. Our study reveals that Cp-degrading enzyme of IRLM.1 is cytoplasmic and 10 μl cytoplasm isolated from 0.05 g dry-weight bacteria can degrade 50% of 2 mM Cp in 2 min. Furthermore, the HPLC analysis showed accumulation of TCP in the medium, revealing that IRLM.1 was able to degrade Cp without being affected by the antimicrobial activity of TCP. Moreover, results show that the IRLM.1 isolate could grow and utilize diazinon and malathion as the sole source of carbon, phosphorus and energy. Thus IRLM.1 can successfully participate in efficient degradation of organophosphorus compounds (OPs).

Key words: Biodegradation, organophosphorus pesticides, chlorpyrifos, isolation.