Influence of heavy metals on the activity of antioxidant enzymes in the metal resistant strains of Ochrobactrum and Bacillus sp.

Three bacterial strains, a cadmium resistant Ochrobactrum sp. designated as CdSP9 and two strains of Bacillus sp. named PbSP6 and AsSP9 resistant to lead and arsenate, respectively were characterized here with respect to their oxidative enzyme activities. The bacterial strains were grown in basal medium supplemented with 50 microg ml(-1) of respective elements to determine the changes in the level of oxidative enzymes. The superoxide dismutase activity increased in all three isolates, but the catalase activity and malondialdehyde concentration were relatively more in CdSP9 than PbSP6 and AsSP9. The glutathione peroxidase, however, remained almost uninduced in CdSP9 but was enhanced in PbSP6 and AsSP9. A possible role of these enzymes in metal tolerance is evident from these results.