Biodegradation of acephate using a developed bacterial consortium and toxicological analysis using earthworms (Lumbricus terrestris) as a model animal

Abstract

This study reports on degradation of the organophosphorus pesticide acephate by a developed bacterial consortium ER, consisting of the bacterial isolates Exiguobacterium sp. BCH4 and Rhodococcus sp. BCH2. The consortium was capable of degrading acephate up to 75.85%, with an initial concentration of 50 mg l−1 within 6 days at 30 °C under static conditions. The effect of various physicochemical parameters, such as pH, temperature, and increasing pesticide concentration on the biodegradation rate, were tested. Biodegradation was monitored by HPLC, FTIR, and GC-MS. The metabolites produced after acephate degradation were characterized and identified as O,S-dimethyl hydrogen thiophosphate (m/z 142), S-methyl dihydrogen thiophosphate (m/z 127), and methyl dihydrogen phosphate (m/z 111), by gas chromatography and mass spectroscopy. Toxicity testing of acephate and its degraded metabolites was performed using the earthworm Lumbricus terrestris as the model animal. The toxicity of acephate and its biodegradation metabolites was tested using various biochemical parameters, such as antioxidant enzyme status (catalase (CAT) and superoxide dismutase (SOD)), lipid peroxidation, protein oxidation, and genotoxicity assay; the eventual conclusion was that the consortium ER possessed significant potential for degradation and detoxification of acephate.