SUPEROXIDE DISMUTASE AND CATALASE ACTIVITIES IN VIBRIO CHOLERAE NON-O1 STRAINS

Antioxidant enzymes are essential for living cells, producing protection from reactive oxygen species such as superoxide, which cause oxidative damage to cell structures. Superoxide dismutase (SOD) and catalase (CAT) activities were determined for three Vibrio strains (Vibrio cholerae non O1/29, V. cholerae non O1/29-T and V. cholerae non O1/26) aerobically grown at 30 degrees C (optimal level) and 10 degrees C (cold stress). All strains tested expressed both antioxidant enzymes under normophysiological and stress conditions, but the cell response is more strain-dependent than dependent on temperature. Levels of SOD in cultures of V. cholerae non O1/26 grown at 30 degrees C were about 2.5 to 9.5-times higher than those in the cultures grown at 10 degrees C. In contrast, SOD activity in V. cholerae non O1/29 increased by 7.5-fold under stress conditions in comparison to that at optimal temperature. The strain V. cholerae non O1/29-T did not show any significant difference in the cell response depending on the growth temperature. CAT activity in cells of V. cholerae non O1/26 and V. cholerae non O1/29-T exhibited a similar tendency suggesting that this enzyme is not included in antioxidant response against cold stress. Contrary to the above observations, V. cholerae non O1/29 demonstrated higher CAT activity in response to temperature downshift. Only one SOD isoenzyme was detected in each of the three Vibrio strains by native PAGE analysis.