RESUMEN
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 O2-. 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 Cu2+ and Zn2+ ions in the nutrient medium. The results are consistent with the assumption that the enhanced resistance of yeast cells to O2- and high concentrations of Cu2+ 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 lipolytica 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.
Asunto(s)
Alcanos/metabolismo , Candida/enzimología , Superóxido Dismutasa/fisiología , Alcanos/farmacología , Candida/efectos de los fármacos , Candida/crecimiento & desarrollo , Catalasa/biosíntesis , Radicales Libres , Glucosa/farmacología , Oxidación-Reducción , Superóxido Dismutasa/antagonistas & inhibidores , Superóxido Dismutasa/biosíntesis , Superóxidos/farmacologíaRESUMEN
A screening procedure for highly thermostable yeast superoxide dismutase was developed. Growth yields at various temperatures were estimated for ten mesophilic and thermotolerant strains, belonging to the genera Saccharomyces, Kluyveromyces and Pichia. Higher yields at 45 degrees C were obtained for K. lactis 90-3 and 90-4. A correlation between the ability to grow at higher temperature and the thermostability of the superoxide dismutase enzyme synthesized was observed. A comparison of the operational stability of the superoxide dismutase of all tested strains suggests that the enzyme of K. lactis strains was more thermostable than that of the other tested microorganisms.