Toxicity of hyperbaric oxygen to yeasts displaying periodic enzyme synthesis.

Abstract

SUMMARY Exponential cultures of Saccharomyces cerevisiae and Candida utilis exposed to oxygen at ten atmospheres did not undergo any further cell division during treatment. All cells ultimately died when the treatment was prolonged for several days. Populations survived considerably longer with ethanol as a carbon source than with glucose. Stationary-phase populations were more resistant than exponentially-growing populations. The cell cycle of S. cerevisiae shows two points of resistance to oxygen toxicity which corresponded to two periods of catalase synthesis in air. These results are attributed to periodic synthesis of protective enzymes.