Mechanisms of Pesticide Biodegradation by Native Microbial Communities in Pesticide-Contaminated Soils of Northern India

Abstract

In Mahendergarh District, Haryana, northern India, intensive agricultural operations have led to significant levels of organophosphate, pyrethroid, neonicotinoid and organochlorine pesticides being The indigenous microbial communities of five pesticide contaminated agricultural soils from Mahendergarh District were characterized and its intrinsic ability to degrade chlorpyrifos, cypermethrin, imidacloprid and endosulfan was studied in laboratory microcosm conditions. The bacteria Bacillus subtilis, Pseudomonas putida, and the fungi Aspergillus niger, Streptomyces sp., Arthrobacter sp. were isolated as dominant degraders. All four pesticides showed first-order degradation, with biotic half-lives (t₁/₂) of 18.3, 24.7, 31.2, and 14.6 days, respectively, compared to two- to threefold longer times for abiotic controls. High level of activities of laccase, peroxidase, hydrolase, dehalogenase and oxidoreductase was observed among the isolates through enzymatic profiling. Metabolite analyses via GC-MS and LC-MS/MS showed sequential ring opening, dechlorination and mineralisation pathways. Results indicate the high biodegradative potential of indigenous microbial consortia in soils of Mahendergarh District and provide opportunities for soil restoration in the northern part of India through bioremediation.