A rod-shaped, Gram-negative chlorpyrifos-methyl (CM) degrading bacterium (designated strain KR200) was isolated from a Korean rice paddy soil and was further tested for its substrate specificity against 11 insecticides and its sensitivity against eight commercial antibiotics. Based on morphological, biochemical, and molecular characteristics, this bacterium showed greatest similarity to members of the order Flavobacteriales and was shown to be most closely related to members of the Chryseobacterium proteolyticum group. Strain KR200 hydrolyzed CM to 3,5,6-trichloro-2-pyridinol (TCP) but could not degrade TCP further. The isolate was also able to degrade chlorpyrifos, dicrotophpos, monocrotophos, and carbaryl at 300 μg mL–1 but diazinon, dimethoate, and furathiocarb at 100μg mL–1. The ability to degrade CM was found to be encoded on the chromosome. Genes encoding resistance to amphotericin B, polymixin B sulfate, and tetracycline were also located on the chromosome. This bacterium merits further study as a potential biological agent for the remediation of soil, water, or crop contaminated with organophosphorus (OP) compounds because of its greater biodegradation activity and its broad specificity against a range of OP insecticides.

• Jun-Ran Kim(Department of Agricultural Biotechnology, Seoul National University)
• Sang-Guei Lee(Department of Crop Life Safety, National Academy of Agricultural Science)
• Yong-Joon Ahn(Department of Agricultural Biotechnology, Seoul National University)