Effect of N+Beam Exposure on Superoxide Dismutase and Catalase Activities and Induction of Mn-SOD in Deinococcus Radiodurans

Though bacteria of the radiation-resistant Deinococcus radiodurans have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. In this report, the superoxide dismutase (SOD) and catalase (CAT) activities produced by these bacteria were measured, and the change of SOD and CAT activities by 20 keV N + beam exposure was examined. Their activities were increased by N + beam exposure from 8×10 14 ions/cm 2 to 6×10 15 ions/cm 2 . The treatment of H 2 O 2 and [CHCl 3 +CH 3 CH 2 OH] and the measurement of absorption spectrum showed that the increase in SOD activity was resulted from inducible activities of Mn-SOD in D. radiodurans AS1.633 by N + beam exposure. These results suggested that this bacteria possess inducible defense mechanisms against the deleterious effects of oxidization.