Full Length Research Paper

Isolation and characterization of a chlorpyrifos-degrading bacterium from agricultural soil and its growth response

M. Surekha Rani¹, K.Vijaya Lakshmi^1* P. Suvarnalatha Devi¹, R. Jaya Madhuri¹, S. Aruna¹, K. Jyothi¹, G. Narasimha² and K.Venkateswarlu³

¹Department of Applied Microbiology, Sri Padmavathi Mahila Visvavidyalayam, Tirupati – 517 502, India.

² Department of Virology, Sri Venkateswara University, Tirupati – 517 502, A.P, India.

³Department of Microbiology, Sri Krishnadevaraya University, Anantapur– 515 003, A.P, India.

*Corresponding author. E-mail: vijaya_k2004@rediffmail.com.

Accepted  20  October, 2007

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.

Key words: Pesticide, chlorpyrifos, Providencia sp. (MTCC No 8099), biodegradation.