Role of superoxide dismutase in the oxidation of N-alkanes by yeasts

Yeast microorganisms from Candida genus are investigated for their superoxide dismutase (SOD) and catalase activity during cultivation on N-alkanes. The later caused a considerable increase of Cu/Zn SOD activity of yeast cells in comparison with glucose. A correlation between SOD and catalase activity existed. It is further observed that cells of Candida lipolytica 68–72 which contain a high level of Cu/Zn SOD were more resistant to lethality of exogenous O 2 −. An over-production of Cu/Zn SOD during the assimilation of N-alkanes by yeasts is also connected to their considerable resistance to increased concentrations of Cu 2+ and Zn 2+ ions in the nutrient medium. The results are consistent with the assumption that the enhanced resistance of yeast cells to O 2 − and high concentrations of Cu 2+ and Zn 2+-ions are due to the increased activity of Cu/Zn SOD and that SOD is involved in the protection of some cellular components. Polyacrylamide gel electrophoresis of Candida lipolutica cell-free extracts revealed the same chromatic bands of SOD activity under growth on glucose and N-alkanes. The type of the carbon source used from yeast cells as a single source of carbon and energy had no influence on the SOD profile of the cell.