Forever panting and forever growing: physiology of Saccharomyces cerevisiae at extremely low oxygen availability in the absence of ergosterol and unsaturated fatty acids

• Published in: FEMS yeast research Vol. 19; no. 6; pp. 1 - 14
• Main Authors: da Costa, Bruno Labate Vale, Raghavendran, Vijayendran, Franco, Luís Fernando Mercier, Chaves Filho, Adriano de Britto, Yoshinaga, Marcos Yukio, Miyamoto, Sayuri, Basso, Thiago Olitta, Gombert, Andreas Karoly
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.09.2019
• Subjects: Anaerobiosis; Bioreactors; Brewer's yeast; Carbon dioxide; Cell viability; Environmental aspects; Ergosterol; Ethanol; Fatty acids; Growth factors; Lanosterol; Oleic acid; Oxygen; pH effects; Physiological aspects; Saccharomyces cerevisiae; Squalene; Unsaturated fatty acids; Yeast; Brazil; anaerobiosis; anaerobic growth factors; oxygen; chemostat cultivation; Saccharomyces cerevisiae
• ISSN: 1567-1364; 1567-1356; 1567-1364
• DOI: 10.1093/femsyr/foz054

ABSTRACT We sought to investigate how far the growth of Saccharomyces cerevisiae under full anaerobiosis is dependent on the widely used anaerobic growth factors (AGF) ergosterol and oleic acid. A continuous cultivation setup was employed and, even forcing ultrapure N2 gas through an O2 trap upstream of the bioreactor, neither cells from S. cerevisiae CEN.PK113–7D (a lab strain) nor from PE-2 (an industrial strain) washed out after an aerobic-to-anaerobic switch in the absence of AGF. S. cerevisiae PE-2 seemed to cope better than the laboratory strain with this extremely low O2 availability, since it presented higher biomass yield, lower specific rates of glucose consumption and CO2 formation, and higher survival at low pH. Lipid (fatty acid and sterol) composition dramatically altered when cells were grown anaerobically without AGF: saturated fatty acid, squalene and lanosterol contents increased, when compared to either cells grown aerobically or anaerobically with AGF. We concluded that these lipid alterations negatively affect cell viability during exposure to low pH or high ethanol titers. Lipid composition is dramatically altered when baker's yeast cells are grown anaerobically without anaerobic growth factors, and these alterations affects negatively cell viability during exposure to stress conditions.