Chlorpyrifos Degradation in Semi-Arid Soil by Pseudomonas fluorescens Strain CD5 Isolated from Manured Soil

ABSTRACT The present paper focused on investigating the potential of indigenous Pseudomonas fluorescens strain CD5 isolated from manure-enriched soil as a bioremediation agent for chlorpyrifos biodegradation in semi-arid soil of Bathinda district of Punjab, India. The soil had sandy loam texture with slightly alkaline pH and low organic matter content of 0.36%. The growth pattern, alkaline phosphatase enzyme production and chlorpyrifos utilization capability of Pseudomonas fluorescens strain CD5 were screened in mineral salt medium and the results revealed degradation of 78.19% of 500 mg L−1 chlorpyrifos within 15 days. The pattern of chlorpyrifos degradation was further studied in natural conditions of semi-arid soil by the Pseudomonas fluorescens strain CD5 and photolysis by sunlight for a period of 105 days. The biodegradation of chlorpyrifos at 500 mg kg−1 sterile soil by Pseudomonas fluorescens strain CD5 was 59.68% in comparison to 26% of photodegradation and enhancing total degradation. The residual chlorpyrifos in sterile soil after biodegradation by Pseudomonas fluorescens strain CD5 under natural light condition was 14.33%. The alkaline phosphatase enzyme activity in soil was found positively correlated with the chlorpyrifos degradation. The Pseudomonas fluorescens strain CD5 can be an effective candidate for the bioremediation of chlorpyrifos-contaminated soil.