Biodegradation of the Herbicide 2，4-Dichlorophenoxyacetic Acid by a New Isolated Strain of Achromobacter sp. LZ35.

In this study， a bacterial strain of Achromobacter sp. LZ35， which was capable of utilizing 2，4-dichlorophenoxyacetic acid (2，4-D) and 2-methyl-4-chlorophenoxy acetic acid (MCPA) as the sole sources of carbon and energy for growth， was isolated from the soil in a disused pesticide factory in Suzhou， China. The optimal 2，4-D degradation by strain LZ35 occurred at 30 °C and pH 8.0 when the initial 2，4-D concentration was 200 mg L. Strain LZ35 harbored the conserved 2，4-D/alpha-ketoglutarate dioxygenase (96%) and 2，4-dichlorophenol hydroxylase (99%)， and catabolized 2，4-D via the intermediate 2，4-dichlorophenol. The inoculation of 7.8 × 10 CFU g soil of strain LZ35 cells to 2，4-D-contaminated soil could efficiently remove over 75 and 90% of 100 and 50 mg L 2，4-D in 12 days and significantly released the phytotoxicity of maize caused by the 2，4-D residue. This is the first report of an Achromobacter sp. strain that was capable of mineralizing both 2，4-D and MCPA. This study provides us a promising candidate for its application in the bioremediation of 2，4-D- or MCPA-contaminated sites.