Mitochondrial and Peroxisomal Contributions to the Energy Metabolism of Saccharomyces cerevisiae in Continuous Culture

Abstract

SUMMARY: Saccharomyces cerevisiae grown in glucose-limited continuous culture at low dissolved oxygen concentrations exhibited high potential respiration rates which reflected the activity of the respiratory enzyme complexes. The development of the mitochondrial respiratory enzymes, unsaturated fatty acids and lipids was highly sensitive to dissolved oxygen even in cells which were growing exclusively by fermentation. A shift to oxidative growth occurred when the oxygen concentration was increased; the apparent oxygen Km for the development of the respiratory complexes was 0.2 μ m. The increase in oxidative metabolism at increased oxygen concentration is related to the development of a functional glyoxylate cycle. Synthesis of the peroxisomal enzymes, including those of the glyoxylate cycle, occurred at significantly higher dissolved oxygen concentration than that of the mitochondrial enzymes.