Abstract: A strain of cypermethrin-degrading bacteria referred to as LQ-3 was isolated from sludge collected from a wastewater outlet of a pesticide plant.Based on morphological,physiological and biochemical characteristics and 16S rDNA sequences analysis(GenBank Accession No.FJ222585),LQ-3 was identified as Starkeya sp..LQ-3 degraded cypermethrin through co-metabolism.When fed with nutrient substances,such as yeast extract,peptone and glucose,LQ-3 could degrade 72.1% of cypermethrin in the medium(20 mg·L^-1) in 5 d.The optimal pH and temperature for the degradation by LQ-3 was 7-8 and 30 ℃,respectively.Strain LQ-3 was also able to degrade other pyrethroids such as cyhalothrin,fenpropathrin,bifenthrin and deltamethrin besides cypermethrin.The enzyme distribution experiment showed that the enzyme responsible for the cypermethrin degradation was extracellular.