The herbicide 2,4-dichlorophenoxy acetic acid (2,4-D) is extensively applied in agricultural fields worldwide and it can contaminate groundwater by direct washing or irrigation. Influx of this pollutant to water supplies can cause pernicious effects on human health and the environment. Many methods are proposed for treatment of this kind of pollution; however, the safest and cheapest method is the use of microorganisms for degradation of the 2,4-D. The aims of this study are the isolation and characterization of 2,4-D degrading bacteria from agricultural soil. The collected soil samples were transferred into a mineral medium containing 2,4-D as a sole carbon and energy source. The flasks were incubated on an orbital shaker at 28 °C and 150 rpm for 5 days. The 2,4-D degrading bacteria were isolated after four times of subculturing into the fresh medium containing 2,4-D. Degradation of 2,4-D was determined by measuring the concentration of chlorine in the growth culture using chloride electrode. The results demonstrated that the isolated bacteria had a potential to degrade 2,4-D as a sole carbon and energy source. In addition, more than 95% of 2,4-D were degraded after 72 hours. The results of this study revealed that these isolates are the appropriate candidates for the degradation of 2,4-D and they can be used for cleaning up the contaminated areas.
