A bacterial strain,designated as LS,was isolated from a contaminated soil and was found to be capable of utilizing quinelorac,bensulfuromnethyl,and a mixture of the two as carbon and energy sources for growth.Strain LS was identified as Ochrobactrum sp.based on its physiological-biochemical properties,16S rDNA sequences,and phylogenetic analysis.The extent of degradation of quinclorac and bensulfuronmethyl at initial concentrations of 1.5 and 0.1 g L-1 was 90% and 67%,respectively,as measured by high performance liquid chromatography (HPLC).When a herbicide mixture of 0.34 g L-1 quinelorac and 0.02 g L-1 bensulfuronmethyl was applied as carbon sources,quinclorac and bensulfuronmethyl were degraded at 95.7% and 67.5%,respectively.It appears that quinclorac is utilized more easily in a mixture than in a single state.The optimal temperature for growth of strain LS was 37℃.Strain LS grew well at pH 6 to 9 and had the highest degradation level for quinclorac and bensulfuronmethyl at an initial pH of 7 and 8,respectively.Addition of 0.25 g L-1 yeast extract could promote the growth and extent of degradation of quinclorac and bensulfuronmethyl by strain LS.Strain LS also showed the capability to degrade other aromatic compounds such as catechol,propisochlor,4-chloro-2-methylphenoxyacetic acid sodium (MCPA-Na) and imazethapy.The isolate LS shows a huge potential to be used in bioremediation for treating complex herbicide residues.