Superoxide dismutase, catalase, and peroxidase in ammonium-grown and nitrogen-fixing Azospirillum brasilense

Publisher Website
Google Scholar
Abstract
Superoxide dismutase (SOD), catalase (CAT) and peroxidase (PER) activities were studied in ammonium-grown and N2-fixing batch cultures of A. brasilense Sp7. PER activity, as measured using o-dianisidine or 3,3''-diaminobenzidine as the H donor, was not significant in most growth conditions. SOD activity increased in response to higher O2 concentrations, but was also present in cells grown anaerobically with nitrate (NO3-) or nitrous oxide (N2O) as electron acceptor. CAT activity increased at lower O2 concentrations and was highest in cells grown anaerobically with NO3- as electron acceptor. Polyacrylamide gel electrophoresis of cell-free extracts reveals only 1 band of SOD activity under each of the physiological conditions employed, compared with three for aerobically grown Escherichia coli K12. This band proved to be Fe-containing SOD (FeSOD) on the basis of inhibitor sensitivity.