Physiological behaviour of Saccharomyces cerevisiae under increased air and oxygen pressures

Saccharomyces cerevisiae, in a pressure batch reactor, coped with higher air (1.2-3 bar) pressures better than with pure oxygen pressures (1.2-3 bar) for an equivalent dissolved oxygen concentration. However, pure oxygen pressure enhanced ethanol production. Both pressures did not influence the type of metabolism followed by the organism which was always oxidoreductive. Growth was inhibited with the increase of air and pure oxygen pressure and almost completely inhibited with 8 bar of pure oxygen. Above 3 bar activities of mitochondrial superoxide dismutase and glutathione reductase increased with air pressure, but cytosolic superoxide dismutase and catalase increased activity only in pure oxygen pressure.