Characterization of a paraquat resistance of Ochrobactrum anthropi JW-2

摘要

The bacterial strain JW-2 which conferred resistance against paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride) was isolated from soil. The strain was identified as an Ochrobactrum anthropi based on its morphological, physiological, biological and fatty acid composition, and was designated as Ochrobactrum anthropi JW-2. We compared paraquat resistance of O. anthropi JW-2 with Escherichia coli JM105. In the presence of 100 mM paraquat, E. coli JM105 was not grown whereas the growth rate of O. anthropi was about 70 percent of control. We compared the sensitivity of O. anthropi JW-2 and E. coli JM 105 to redox-cycling compounds such as paraquat, plumbagin or menadione, which are known to exacerbate superoxide generation. O. anthropi JW-2 did not show cross-resistance to plumbagin or menadione. Superoxide dismutase activity was increased in paraquat-treated E. coli JM105 while it was not increased in O. anthropi JW-2. These results suggest that the mechanism of paraquat resistance in O. anthropi JW-2 is probably due to selectively decreased permeability toward paraquat by membrane protein.