The enzymatic defence system in the 2 yeasts Kluyveromyces marxianus and Rhodotorula glutinis, differing in their mode of oxygen uptake and energy generation, was characterized and compared with the well-studied facultatively fermentative Crabtree-positive Saccharomyces cerevisiae strain. Twofold higher superoxide dismutase (SOD) and catalase activities were detected in K. marxianus and R. glutinis when cells were cultured on glucose. Further increases of 10%-15% in SOD activity and 30%-50% in catalase were measured in all studied yeasts strains after transfer to media containing ethanol. An evaluation of the ratio of Cu/Zn SOD / Mn SOD was performed as a measure of the oxidative metabolism. A 20% decrease was observed when the respiratory source of energy was ethanol, with the lowest ratio being observed for the oxidative type of K. marxianus yeasts. Electrophoretic analysis revealed that all tested strains possess active Cu/Zn and Mn SODs. A reverse electrophoretic mobility pattern of K. marxianus and R. glutinis SOD enzymes was observed in comparison with the same couple in S. cerevisiae. The investigation of electrophoretic profile of catalase enzymes showed that alongside their different taxonomic status and fermentative capacity, all tested strains possess 2 separate catalases. The role of antioxidant enzymes in preventing oxidant-induced cytotoxicity (treatment with hydrogen peroxide, paraquat, and menadione) was shown.

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Hansenula polymorpha CBS 4732, cultivated on media containing glucose, glycerol or methanol as carbon source has been investigated for specific activity of Superoxide dismutase (SOD) enzymes during batch -wise cultivation. Furthermore cell free extract from the analyzed strain cultivated on different carbon sources were subjected to 8% native PAGE. One band corresponding to sensitive of KCN Cu/Zn SOD with Rm 0.29 is inhibiting in all samples. After inhibition of cyanide sensitive Cu/Zn SOD, three bands specifically stained for SOD activity, corresponding to Mn SOD are observed in samples obtained by H. polymorpha cultivated on medium containing methanol. Two bans are retaining in glucose and glycerol grown cells. This data suggest that probably in H. polymorpha yeasts appears multiple enzyme forms of Mn SOD enzyme. Multiple enzyme forms become more stable and do not disappear after 1 min at 75°C. One band with Rm 0.34 in all yeast samples cultivated on methanol, glucose and glycerol, remains till heating at 75°C for 10 minutes.