Biosynthesis of superoxide dismutase and catalase in chemostat culture of Saccharomyces cerevisiae

Summary The effects of oxygen (100%), paraquat (0.5 mM), and copper (0.1 mM) on the growth and the biosynthesis of the antioxidant enzymes, superoxide dismutase (SOD) and catalase, were studied in Saccharomyces cerevisiae grown in glucose-limited chemostat cultures. The effect of dilution rates (D, h⁻¹) on cell mass, glucose consumption, ethanol production, oxygen uptake, and specific activities of SOD and catalase were also investigated at each steady state. SOD was optimally produced at D-values between 0.22 and 0.26 h⁻¹ in the presence of oxygen or paraquat, and at D-values greater than 0.17 h⁻¹ when copper was used. On the other hand, catalase activity decreased with increasing D-values. However, the presence of copper or 100% oxygen repressed catalase activity at low D-values (D<0.1 h⁻¹), and decreased the rate of oxygen uptake at all D-values tested. The presence of paraquat affected the rate of oxygen uptake only at high D-values (D>0.22 h⁻¹). We also studied the effect of oxygen concentration on the biosynthesis of SOD and catalase at D=0.1 h⁻¹. The data clearly show that synthesis of SOD and catalase, though correlated with changes in oxygen tension, are independent of one another. Paper Number 10871 of the Journal Series of North Carolina Agricultural Research Service, Raleigh, NC 27 695. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named, nor criticism of similar ones not mentioned