Characterization of 2,4-D degrading bacteria isolates from herbicide contaminated soils in the central rift valley of Ethiopia

Abstract

The escalating issue of herbicide pollution poses significant risks to environment, biodiversity and human health. Because conventional physicochemical treatments are often expensive, energy intensive and prone to generating toxic byproducts, this research focused on a biological treatment alternative. The study sought to isolate, characterize and identify bacteria capable of degrading 2,4-D from herbicide contaminated soil for the purpose of bioremediation. The study involved screening on 2,4-D–amended media and GC-MS analysis to assess degradation capabilities. MALDI-TOF, and 16S rRNA sequencing were used for bacteria species identification. The findings indicated that while ten species survived at 3000 ppm of 2,4-D amended solid agar media, only four species, Serratia nevei, Enterobacter asburiae, Serratia marcescens, and Bacillus velezensis could tolerate concentrations up to 5000 ppm on 2,4-Damended agar solid media. These high-tolerance isolates demonstrated optimal growth conditions at a pH range of 7–10 and temperatures between 30–37°C. Among the four species, S. marcescens (AAUB-FSB3) demonstrated the highest degradation efficiency, achieving 89.70% degradation of 3000 ppm 2,4-D in 100% 2,4-D treated broth media. The significant 2,4-D degradation ability of this bacterium species suggests its promising potential for bioremediation of 2,4-D pollution, warranting further field evaluation.