Microbial Degradation of Organophosphate Pesticides in Polluted Soil: Mechanisms, Efficiency, and Environmental Impact

Abstract

The widespread use of organophosphate pesticides in agriculture has resulted in significant soil contamination leading to environmental and health concerns. This study aimed to isolate and identify microbial strains capable of degrading organophosphate pesticides, particularly chlorpyrifos from contaminated soils and evaluate their degradation efficiency under controlled conditions. Microorganisms were isolated from pesticide-contaminated soils collected in January 2024 from agricultural fields in Anyigba, Kogi State, Nigeria (7°29'38"N 7°10'54"E). The isolated strains were tested for their ability to degrade chlorpyrifos a commonly used organophosphate pesticide. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the degradation process, while soil health parameters such as organic matter content and pH were monitored. All experiments were performed in triplicate and analyzed using one-way analysis of variance (ANOVA), followed by Tukey's post-hoc test. Results indicate that microbial strains, particularly Pseudomonas fluorescens and Bacillus cereus degraded 82% and 75% of chlorpyrifos, respectively within 21 days under optimal conditions (30°C, pH 6.5). Soil pH increased from 6.2 to 6.8, while organic carbon content improved by 15% (from 1.80% to 2.07%) following microbial treatment. GC-MS analysis revealed complete mineralization pathways with 3,5,6-trichloro-2-pyridinol as the major intermediate metabolite. This research highlights the potential of microbial bioremediation as an eco-friendly and cost-effective method for managing pesticide-polluted soils with implications for sustainable agriculture and environmental conservation.