Biodegradation of chlorpyrifos organophosphorous pesticide using Aeromonas hydrophila,/i> isolated from selected agricultural wastewater in Kaduna State

Abstract

Chlorpyrifos are broad-spectrum organophosphorus pesticides used excessively for agricultural purposes to fight insects. The presence  of such toxic compounds in watercourses exhibits harmful threats to the environment. The technology of bio-removal (or  biodegradation) is nowadays the alternate method for environmental curing. The present study aimed to isolate and identify bacterial  strains with strong capabilities of biodegrading such pesticides in wastewater from Nassarawa and Hayin Danmani, Kaduna State.  Aeromonas hydrophila was isolated from agricultural wastewater and identified based on morphological, biochemical tests, and 16S  rRNA analysis. The degradation conditions were optimized at 30°C and pH of 7. Preliminary screening assessed growth via optical density.  Degradation efficiency was measured in inoculated samples compared to controls, with Chlorpyrifos concentration and  degradation rates evaluated. Chlorpyrifos concentrations in water samples NA1-HB1 ranged from 2.71 ± 0.11 to 131.8 ± 0.2. Aeromonas  hydrophila effectively degraded Chlorpyrifos, with optimal growth observed at an optical density of 0.74 ±0.002. Degradation was faster in inoculated samples, achieving a 73.6 % degradation rate at a Chlorpyrifos concentration of 30 mg/L. The metabolite 3, 5, 6- trichloro-2- pyridinol (TCP), responsible for Chlorpyrifos degradation was detected. Aeromonas hydrophila can efficiently degrade Chlorpyrifos in  wastewater, utilizing it as a carbon source. Further research should explore more soil microbiota with Chlorpyrifos (CP) utilization  capabilities and investigate the metabolic pathway of Chlorpyrifos degradation.