In the present communication, we have reported a novel, simple, fast, convenient and sensitive method for determination of Chlorpyrifos, an organophosphorus pesticide based on organophosphorous hydrolase (OPH) activity. Bacillus flexus, accession number (MF800923) strain was isolated from chlorpyrifos contaminated soils of Punjab, India exhibiting significant OPH activity. Viable and actively growing bacterial cells were immobilized using Sol-Gel immobilization method. As a result of OPH activity, chlorpyrifos was mineralized into TCP (3-5-6 trichloropyrinidol), an metabolite of CP. A sensitive colorimetric based method was developed for the detection of TCP generated upon CP mineralization. Detection of CP was found to be in the linear concentration range 1 mg/L - 100 mg/L. Accuracy and reliability of developed biosensor was also validated and percent accuracy was calculated in the range of 94-96 %. Monitoring of detection of CP by naked eyes, low cost and easy operation were the key attributes of the developed biosensor. Under the optimized experimental conditions, the biosensor exhibited a lowest detection limit of 0.01 mg/L and response time of fifteen minutes. Developed system was also applied for determination of CP residues in the real soil samples. Hence, a highly sensitive and rapid whole cell based biosensor, holding the promise for detection of CP content in the water and agricultural soils has been developed. Outcome of present work facilitate development of rapid and high-throughput screening of CP.
