Antioxidant Defense Mechanisms in Pseudomonas aeruginosa : Role of Iron-Cofactored Superoxide Dismutase in Response to UV-C Radiations

The role of SOD gene in response to UV-C radiations was studied in Pseudomonas aeruginosa . Firstly, our results showed that the inactivation of sodM and/or sodB genes decreases the resistance of P. aeruginosa after exposure to UV-C rays. Furthermore, our results showed that SOD activity is dose dependant in all strains. However, significant increase in SOD activity was only shown at UV-C exposure time of 5 min in sodB mutant. At an elevated dose equivalent to 30 min of exposure, significant increase in SOD activity was observed in sodM . Catalase activities showed significant decrease in WT and in sodB mutant after an exposure time of 30 min. CAT enzyme was present at higher levels than SOD, reflecting that alternate enzymes such as POX, is poorly associated with CAT activity, and an increase in POX activity is related to increase in stress tolerance. The overall results showed that sodB gene has an important protective role against UV-C radiations in P. aeruginosa , compared to SodM isoform.