Biochemical degradation of some pesticides in agricultural soil of Gaza strip - Palestine
عبدالله بشير , عمار فوزي مطر, مازن حمادة
معهد المياه والبيئة-جامعة الازهر - غزة-جامعة الازهر - غزة · فلسطين
This work deals with a biochemical degradation of three pesticides: diuron, carbaryl and glyphosate. Analysis was conducted of 6 soil samples collected from two agricultural places in the Gaza Strip (open fields and inside greenhouse) according to soil type map. The samples were treated, and 82 types of bacterial strains were isolated. 14 of them showed good ability of growth when using the tested pesticides as a sole source of nitrogen and carbon. The identified bacteria belong to the following genera; Bacillus, Corynebacterium, Pseudomonas, Morganella and Aeromonas. Three bacterial strains were used as representative bacteria in studying the biodegradation rate of diuron, carbaryl and glyphosate on solid and liquid media. The bacterial strains were identified through cultural and biochemical characterization as Bacillus coagulans, Morganella morganii and Corynebacterium kutseri. These were capable to degrade diuron, carbaryl and glyphosate. The three bacteria were inoculated with each of the three pesticides at a concentration of 150 ppm for 11 days. The biodegradation rate of the three pesticides on liquid media was determined using UV spectrophotometer. Also the remaining concentrations of the tested pesticides were chromatographically measured using TLC after optimization of solid phase extraction conditions. The results showed that the bacteria Bacillus coagulans had a high efficiency to degrade carbaryl with rate 98.71% and rate 71.96% with diuron and less efficiency for glyphosate with degradation rate 20.50%. Bacteria Morganella morganii showed moderate rate of degradation of the three pesticides (diuron 45.54%, carbaryl 87.37% and 47.69% for glyphosate), while the bacteria Corynebacterium kutseri showed the best efficiency for glyphosate with rate 77.90%, and moderate efficiency for carbaryl with rate 47.59%, and the least for diuron with rate 27.25%.