Integrated optimization and environmental application of chlorohydrolase-positive bacterial isolates for enhanced atrazine degradation and genotoxicity assessment

Atrazine (ATZ), a widely used broad-leaved weed management chemical in agriculture, with a half-life of 30–740 days, poses a threat to the ecosystem. Its residue is found in various levels of soil and aquatic ecosystems. In this study, three new strains were identified and used to treat effectively, thereby reducing toxicity and rapid degradation. Bacillus mycoides strain (P2), Pseudomonas sp. strain(P3), and Pseudomonas furukawaii (P6). The degradation efficiency was found to follow the order P3 > P2 > P6. Over a twelve-day experiment, all strains demonstrated atrazine utilization, with a half-life period ranging from 65.53 to 102.32 days by using pseudo-first-order kinetics. Response surface methodology was employed to optimize the biodegradation parameters, including atrazine dosage, pH, and temperature, for all three strains. The investigation revealed that the optimum conditions for atrazine degradation by all strains were pH 7.4, temperature 32 ± 2 °C, and concentration 100 mg/L. Gas chromatography-mass spectrometry results identified the major degradation products of atrazine, including Deisopropylatrazine (DIA), Deethylatrazine (DEA), and Cyanuric acid (CNA) at RT 6.46, 12.22, and 14.22, respectively, also closely align with the predicted statistical design model. All three isolated strains exhibited hydrolysis of Atrazine, suggesting the presence of intracellular Atrazine chlorohydrolase enzymes. Genotoxicity studies on the degradation products depicted toxicity in the order Atrazine>DEA>DIA>CNA. These atrazine-biodegrading isolates show promise as effective remediators for atrazine-contaminated agricultural soils and crop fields in terms of laboratory efficacy and practical application, as well as for environmental cleaning processes involving other pesticides.