Simultaneous degradation of organophosphorus and organochlorine pesticides by bacterial consortium

Abstract

Several researchers have focussed on degradation of pesticides by microorganisms, which is the most viable option in remediation of agricultural soil. However, very few have illustrated the degradation of mixed pesticides. Hence, in the present investigation biodegradation of a mixture of both organophosphorus and organochlorine pesticide directed by microbial consortium was carried out in a fermentor–bioreactor system. The pesticides chosen were chlorpyrifos, monocrotophos (organophosphorus) and endosulfan (organochlorine). In order to accomplish an effective degradation, the microorganisms were isolated from agricultural fields which were previously exposed to the pesticides mentioned above. The bacteria were isolated by minimal meda with the individual pesticide as the only carbon source. The individual strains were identified by morphological, biochemical and 16S rRNA characterization. The bacterial consortium comprised of 10 organisms which were as follows: Alcaligenes sp. JAS1, Ochrobactrum sp. JAS2, Sphingobacterium sp. JAS3 which were screened and selected from chlorpyrifos contaminated soil, Enterobacter ludwigii JAS17, Pseudomonas moraviensis JAS18 and Serratia marcescens JAS16 which were isolated from monocrotophos spiked soil and Klebsiella pneumoniae JAS8, Enterobacter cloacae JAS7, Halophilic bacteria JAS4, Enterobacter asburiae strain JAS5 were obtained from endosulfan persistent soil sample. The fermentor–bioreactor system containing 2L of sterile minimal medium supplemented with 300mgl−1 of chlorpyrifos, 1000mgl−1 of monocrotophos, 1000mgl−1 of endosulfan as the only source of carbon and inoculated with 20ml of bacterial consortium (approximately 3×106cellsml−1). The HPLC and GC–MS studies were performed to record the degradation of mixed pesticides.