Abstract

M. Surekha Rani, K.Vijaya Lakshmi* P. Suvarnalatha Devi, R. Jaya Madhuri, S. Aruna, K. Jyothi, G. Narasimha and K.Venkateswarlu

A soil bacterium capable of utilizing chlorpyrifos as sole carbon source was isolated by selective enrichment on mineral medium containing chlorpyrifos. The bacterial isolate, designated MS09, was identified and characterized as a strain of Providencia stuartii based on biochemical characteristics and 16S rRNA sequence analysis. Growth studies showed that P. stuartii strain MS09 utilized chlorpyrifos to grow in Luria-Bertani broth containing different concentrations of chlorpyrifos at 50 -700 mg/L. However, the optimum concentration that supported bacterial growth over 24 h was found to be 50 - 200 mg/L chlorpyrifos. When compared with the control, a significant increase in bacterial growth was noted at a low concentration of chlorpyrifos (50 mg/L), whereas at higher concentrations (300 - 700 mg/L) an increased lag phase was observed, without inhibiting growth of the pesticide- utilizing bacterium. A literature survey revealed that no data is available regarding the role of P. stuartii on pesticide biodegradation.