Functional Analysis of Chlorpyrifos Biodegradation in Agricultural Soils Augmented with a Three-Strain Bacterial Consortium

Chlorpyrifos (CP) is a widely used organophosphate (OP) insecticide and a potent environmental neurotoxin. This research focuses on the potential of bacteria, both native to agricultural soil and part of a designed consortium composed of laboratory strains, to completely degrade CP and its toxic metabolites. Metabolite production and degradation kinetics analysis through gas chromatography-mass spectrophotometry (GCMS) analysis was conducted on native soil samples and compared to soil spiked with different combinations of bacterial consortia over 7 days to determine the effectiveness of CP degradation in both non-augmented and augmented soil. GCMS analysis of augmented soil samples inoculated with putative microbial CP degradation activity identified four CP metabolites, including 3,5,6-trichloropyridinol (TCP), phosphorothioic acid, fumaric acid, and ethanol. Non-augmented ranch and crop field soil also displayed a greater native degradation capacity than garden soil, possibly due to greater pesticide exposure. CP-inoculated soil spiked with a 3-strain consortium exhibited the highest degradation rate, with 78.55% of CP degraded within 48 h. Overall, degradation kinetics for augmented and non-augmented soil samples showed that CP had an average half-life of 1.03 and 5.45 days, respectively. The outcome of this study suggests that while native agricultural populations are capable of CP degradation, supplementing contaminated soil with a bacterial consortium consisting of Pseudomonas putida CBF10-2, Ochrobactrum anthropi FRAF13, and Rhizobium radiobacter GHKF11 could be a highly efficient and safe biological approach to facilitating rapid and efficient CP degradation in agriculture.