Accelerated Degradation of four Organophosphorus Insecticides by Malathion Tolerant Aspergillus niger MRU01 a Soil Fungus

Abstract

Insecticides are widely used in agriculture, horticulture, medicine, and industry, as well as domestically. Increased insecticide application has been attributed to higher agricultural productivity and lower infield and postharvest crop loss in the twentieth century. Malathion is a very commonly used organophosphorus (OP) insecticide applied in over 100 food crops in agriculture and post-harvest storage. Different species of Aspergillus have shown their efficiency to degrade OP chemicals. A malathion tolerant Aspergillus niger MRU01, developed by prolonged malathion exposure, was tested for its efficiency to remove malathion as well as three other commonly used OP insecticides, viz., parathion, chlorpyrifos and dimethoate. The tolerant strain showed growth efficiency as well as enhanced production of phosphatases and esterase enzyme as compared to untreated and treated wild type (A. niger ATCC16404). The removal of malathion was 29% and 68%, in the wild type and the tolerant strain, respectively during five days. The tolerant strain was also able to remove dimethoate (63%) and chlorpyrifos (54%) with high efficiency while a low rate of removal of parathion (33%) was observed. The strain can be tested in the microcosms more specifically for bioremediation of other OP insecticides before its application in the field.