SUPEROXIDE DISMUTASE IN FACULTATIVELY ANAEROBIC BACTERIA: ENZYME LEVELS IN RELATION TO GROWTH CONDITIONS

Abstract

Specific activities of superoxide dismutase (SOD) were found to range limitedly from 9.3 to 18.3U/mg protein among 11 typical strains of facultatively anaerobic bacteria grown under the same condition. All of the SOD's in these bacteria were resistant to 1mM KCN, suggesting the exclusion of cupro-zinc-SOD. Every bacterium examined had SOD's resistant to 5mM H₂O₂, suggesting manganese-SOD's. Some had H₂O₂-sensitive SOD's which were presumed to be iron-SOD's. Several cultural factors were examined in their effect on SOD activities in Escherichia coli B, a typical facultative anaerobe. Aeration and manganese sulfate supplementation to media clearly affected both the levels and the acrylamide gel electrophoretograms of SOD's. Aeration was proved to induce two of the three isoenzymes, the third-SOD and manganese-SOD. Manganese sulfate was proved to promote the induction of manganese-SOD by aeration.