Isolation, Characterization and Growth Response Study of Chlorpyrifos Degrading Bacteria from Cultivated Soil

In the present work, six bacterial isolates capable of degrading chlorpyrifos (an organophosphorus pesticide) were obtained by enrichment from soil samples collected from the cultivated fields of Rajkot district of Gujarat State. The isolates were capable of growing in the presence of chlorpyrifos, in the concentration range of 60-100 mg/L. The highest value of MIC (100 mg/L) was reported for bacterial isolate GCC-1. The viable cell count of all six isolates was in the order of 10 per gram of soil in presence of chlorpyrifos (50 mg/L). The optimum growth temperature for the bacterial isolates varied between 25C and 37C, however, for majority of the isolates it was 37C. The optimum growth pH for the bacterial isolates was between 6.0 and 8.0; however, it was 7.5 for three out of six isolates. Therefore, optimization of temperature and pH is absolutely essential before large scale culture of the bacterial isolates capable of degrading chlorpyrifos.