Toxicologie environnementale et analytique

Pleurotus ostreatus as a Biodegradator for Organophosphorus Insecticide Malathion

Abstract

Ganash MA, Abdel Ghany TM and Reyad AM

Excessive and continuous use of organophosphorus insecticides as well as malathion has led to the contamination of ecosystems in several rejoins of the world. For its degradation in the ecosystems usage of the microbes has been proved to be the effective method for controlling ecosystems pollution. Biodegradation of pesticides by using microbes have more advantages over the conventional methods. In the present investigation therefore attempts have been made to make use of white rot fungus Pleurotus ostreatus for malathion degradation. Malathion rest quantity at 5, 15 and 25 days was 40.5, 22.6 and 11.8 (μg/100 mL) with degradation % 19.0, 54.8 and 76.4 respectively at initial concentration (50 μg/100 mL). Lignin peroxidase, manganese peroxidase, and laccase production was stimulated with the presence of malathion. At 25 μg/100 mL malathion, productivity of lignin peroxidase, manganese peroxidase, and laccase was 0.51, 0.57 and 4.30 U/ml respectively compared with the control (growth medium without malathion). At low concentrations of malathion (25 and 50 μg) P. ostreatus productivity of these enzymes was more, but at high concentration of malathion the productivity was less than control. Addition of lignin compound induced the productivity of ligninolytic enzymes and therefore the biodegradation of malathion was increased. GC/MS analysis revealed the presence of many products as a result of malathion biodegradation including diethyl mercaptosuccinate, methy l,2-(Dimethoxyphosphoryl)-2-(1,2,3- thiadiazol-4-yl) acetate, 3,4-dihydrothienyl (3,4,b)-5-carboxythiophene, Butanedioic acid, 2,2'-Thiodisuccinic acid; 1,1-Dimethyltetradecyl hydrosulfide and Disulfide, di-tert-dodecyl.