A Genomic And Functional Analysis On The Impact Of Commercial Pesticides On Chlorpyrifos Degradation By Three Bacterial Consortia

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2022-01

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Abstract

Chlorpyrifos is an organophosphate pesticide widely used in agriculture. It is a potent environmental neurotoxin. There are many biological approaches to eradicate the impact of chlorpyrifos contamination from our environment. This research project focused on the potential bacterial degradation of the commercial formulation of chlorpyrifos and assessed how different commercial adjuvant stabilizers could impact the biodegradation process. While it had been observed that a consortium of three bacterial strains consisting of Pseudomonas putida, Ochrobactrum anthropi and Rhizobium radiobacter could break down chlorpyrifos, it was not clear how it interacted with a designated commercial formulation, how the additional compounds of commercial formulation could alter the breakdown of chlorpyrifos. RAST (Rapid Annotation using Subsystem Technology) server had been used to identify the putative chlorpyrifos degradation biomarkers. Gas chromatography and mass spectrometry analysis were performed on bacterial samples inoculated by chlorpyrifos for 5 days to determine the effectiveness of chlorpyrifos in the bacterial solution. Genomic analysis of the bacterial strains revealed a series of OPHC2 like Metallo-β-lactamase (MBL) enzymes. GCMS analysis of bacterial samples contaminated with chlorpyrifos supported microbial biodegradation activity and showed three chlorpyrifos metabolites, including 3,5,6- trichloro-2-pyridinol (TCP), fumaric acid, and Ethanol. The degradation kinetics for bacterial consortium treated with commercial Chlorpyrifos and pure Chlorpyrifos was 0.79 d-1, and 1.06 and half-life were 21 hours and 15.6 hours, respectively. It had been proven that chlorpyrifos inoculated bacterial samples containing three bacterial strains designed by Dr. Iyer’s laboratory exhibited a significant level of biodegradation of pure chlorpyrifos. Therefore, it had been assumed that Bacterial consortium treated with commercially formulated chlorpyrifos could also be a highly effective and safe biological approach to enabling rapid chlorpyrifos biodegradation. However, this study's outcome suggested that the adjuvants' inclusion in commercial chlorpyrifos had a small but significant negative impact on the biodegradation rate, increasing the half-life of 15 hours to 21 hours compared to the pure biodegradation rate.

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CP(chlorpyrifos), OP(organophosphate)

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