Loveleen Kaur and Dinesh Raj Modi*
Department of Biotechnology, Babasaheb Bhimrao Ambedkar University, Raibareli Road, Lucknow-226025, India
Cite this article: Kaur, L., Modi, D.R., 2025. Enhanced biodegradation of phenoxyacetic herbicides 2,4-d and 4-chloro-2-methylphenoxyacetic acid by bacterial strains under variable environmental conditions. J. Appl. Sci. Innov. Technol. 4 (1), 30-36.
Abstract
Phenoxyacetic acid herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 4 chloro-2-methylphenoxyacetic acid (MCPA) are widely used in agriculture but pose significant environmental risks due to their persistence and potential toxicity. This study investigates the growth dynamics and degradation efficiency of bacterial strains exposed to varying concentrations of 2,4-D and MCPA under different pH and temperature conditions. Growth was monitored through optical density measurements (OD600), while degradation efficiency was calculated based on herbicide concentration decline over time. In control conditions, bacterial growth showed a typical sigmoidal curve, whereas the presence of herbicides slightly inhibited early growth, particularly for 2,4-D. Optimal bacterial growth and degradation occurred at neutral to slightly alkaline pH (pH 7–8), with significantly reduced growth at acidic pH (pH 5). Temperature profiles revealed that 30°C and 40°C supported the highest bacterial activity, while extreme temperatures (20°C and 50°C) negatively impacted growth in 2,4-D treatments. Interestingly, MCPA-exposed cultures exhibited more stable growth across varying conditions. Herbicide concentrations ranging from 300 to 700 mg/L showed minimal effect on degradation efficiency, which remained above 99% for both 2,4-D and MCPA. However, higher concentrations marginally suppressed bacterial growth. The findings suggest that the tested bacterial strains possess strong adaptive mechanisms and metabolic versatility for degrading phenoxyacetic herbicides, even under stressful environmental conditions. This study underscores the potential of microbial bioremediation as an effective approach for detoxifying herbicide-contaminated environments and highlights critical factors influencing biodegradation efficiency. These results contribute valuable insights into optimizing field-scale applications for sustainable agricultural practices.
Kewwords: Xenobiotics; Bioremediation; 2,4-D; Agricultural contaminants; MCPA
Scope: Biotechnology
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