Journal of Pure and Applied MicrobiologyVol. 3 No. 2

In situ Bioremediation of Chlorpyrifos in Cotton Fields: Possible Role of Plant-Microbe Interaction

C. Vidya Lakshmi* and N. Tejo Prakash

Department of Biotechnology and Environmental Sciences, Thapar University, Patiala - 147 004, India.

Received on 12 April 2009 and accepted on 09 June 2009

 

ABSTRACT

Indiscriminate use of oganophosphate pesticides has made their mitigation from soil essential. Among the pesticides, chlorpyrifos is a widely used broad-spectrum organophosphate effective in controlling a variety of insects. In the present study, Pseudomonas fluorescence and Pseudomonas aeruginosa were inoculated in the fields with cotton plants to determine the role of the plant-microbe interaction in the degradation of chlorpyrifos in the contaminated plots. After 25 days of inoculation, P. fluorescence and P. aeruginosa degraded 78 and 85% of chlorpyrifos in plots without cotton plants whereas 99% degradation of chlorpyrifos was observed in soil, where cotton plants were inoculated with either Pseudomonas fluorescence or Pseudomonas aeruginosa as compared to un-inoculated control soil. REP-PCR showed an increase in population of P. fluorescence from 1.52 X 107 at the time of inoculation to 2.0 X 107 in plots without crops whereas 3.1 X 107 in plots with cotton plants on day 25. Similar trend was shown by the P. aeruginosa. Product formation indicated the appearance of 3, 5, 6-trichloro-2-pyridinol (TCP), the major metabolite of chlorpyrifos degradation, in the plots inoculated with P. aeruginosa, which disappeared to negligible amounts.

Keywords : Plant-microbe interaction, chlorpyrifos degradation, REP-PCR, P. aeruginosa and TCP.