The effects of pH, temparature, diazinon concentration and bacterial inoculum density on diazinon biodegradation rate by Cupriavidus sp.CL36_M4 and <i> Achromobacter xylosoxidans </i> BT4_L1 isolation from upland crop-rice farming system soils
Keywords:Achromobacter xylosoxidans BT4_L1, Cupriavidus sp.CL36_M4, diazinon, Upland crop-rice farming system.
Biodegradation is an efficient and feasible method for decreasing soil pollution caused by diazinon. This study aims to evaluate the effects of temperature, pH, diazinon concentration and inoculation density on the growth of of Cupriavidus sp. CL36_M4 and Achromobacter xylosoxidans BT4_L1 and their diazinon biodegradation rates. The experimental design was completely randomized under laboratory conditions. Observations were made after 30 days of incubation. pH value, temparature, diazinon concentration and bacterial inoculum density were measured using pH meter, thermometer, HPLC and drop plate count, respectively. Two strains CL36_M4 and BT4_L1 produced the highest numbers of cells when grown at 30°C in a pH 7 medium with diazinon concentration of 20–50 ppm. These two bacterial strains showed their most effectiveness in degrading diazinon when grown at 30°C (with degradation rate of 0,70–1,03% day-1), pH 7 (with degradation rate 0,72–1,02% day-1), diazinon concentrations of 20 ppm (with degradation rate of 0,67–0,97% day-1) and inintial innocuation density of 106 CFU/mL (with degradation rate of 0,74-1,18% day-1).