BIODEGRADATION OF PROFENOFOS BY Pseudomonas STRAINS UNDER PRESENCES OF OXYGEN AND NITRATE

Abstract

Profenofos pesticide contaminated in groundwater with presence of nitrate was an problematic issue potentially found in agricultural countries. This study aimed to investigate profenofos biodegradation under presence of nitrate compared to the condition with oxygen. Three isolates, Pseudomonas plecoglossicida strain PF1 (PF1), Pseudomonas aeruginosa strain PF2 (PF2) and Pseudomonas aeruginosa strain PF3 (PF3), were used. In this research, concentrations of profenofos (10-150 mg/L) and nitrate (100-300 mg/L) were varied. Duplicate batch experiments were conducted using incubating shaker at 150 rpm and room temperature for 6-8 days. The results showed that removal efficiency percentages under presence of oxygen by PF1, PF2 and PF3 ranged from 38.14 to 55.39, 31.62 to 61.22 and 34.72-63.81%, respectively whereas PF1, PF2 and PF3 was removed profenofos from 27.50 to 45.33, 39.09-75.36 and 13.78 to 48.89% under presence of nitrate, respectively. The profenofos degradation kinetics followed the first order kinetic reaction. Strains PF1 and PF3 degraded profenofos under presence of oxygen better than presence of nitrate while PF2 utilized profenofos under presence of nitrate superior than presence of oxygen (For microbial growth, strains PF1, PF2 and PF3 grew from 104 to 108 CFU/ml followed the first kinetic order for both presence of oxygen and nitrate). Although nitrate was used as an electron acceptor during profenofos degradation, nitrate could inhibit the profenofos biodegradation as well. For intermediate metabolite monitoring, under presence oxygen and nitrate, 4-bromo-2-chlorophenol and 1,1-diethylethylphenol were found. Moreover, triethyl phosphate was also found as the metabolite on profenofos degradation under presence of nitrate. This study indicated that strains PF1, PF2 and PF3 could be applied in the profenofos-contaminated environment including groundwater containing nitrate. The cultures are promising for profenofos bioremediation in the future.