Biodegradation of Cypermethrin by Two Isolates of Pseudomonas aeruginosa

Abstract

Two local bacterial isolates were isolated from agriculture soil contaminated with cypermethrin from AlAbaeje village in Baghdad city, these fields were already sprayed with cypermethrin for past few years. Primary screening was done to test bacterial ability to growth and resistance to cypermethrin by using nutrient agar plates containing 500 mg L^-1 cypermethrin as a sole source of carbon and energy, and incubation at 37 ºϹ for 72 hours. Secondary screening results showed that these two bacterial isolates have the ability to grow and resistance cypermethrin concentration till 3600 mg L^-1 in solid MMSM. If we increase concentration above 3600 mg L^-1 bacterial isolate can’t tolerate and grow in it. According to VITEK 2 compact results the dominate isolate in soil contaminated with cypermethrin was Pseudomonas aeruginosa about 87.5%. The optimum conditions (pH, temperature and incubation period) for growth of two selected isolates and biodegradation of cypermethrin were examined. The results indicated that the best growth obtain at pH 7 under 30 ºC for 14 days. In lab experiment and under optimal conditions, cypermethrin biodegradation was measured by using FTIR and GC-MS analysis. The results shown that P. aeruginosa 1 was the best isolate for degrading cypermethrin  with percentage 87.9% while P. aeruginosa 2 with degrading percentage 80%.