Fine measurement of ergosterol requirements for growth of Saccharomyces cerevisiae during alcoholic fermentation

• Published in: Applied microbiology and biotechnology 2005-08, Vol.68 (2), p.266-271
• Main Authors: DEYTIEUX, Christelle, MUSSARD, Ludivine, BIRON, Marie-José, SALMON, Jean-Michel
• Format: Article
• Language: English
• Subjects: Alcohols - metabolism; Anaerobiosis; Analysis; Biological and medical sciences; Biological Assay - methods; Biology of microorganisms of confirmed or potential industrial interest; Biosynthesis; Biotechnology; Brewer's yeast; Culture Media; Ergosterol; Ergosterol - analysis; Ergosterol - metabolism; Fermentation; Fundamental and applied biological sciences. Psychology; Life Sciences; Lipids; Microbiology and Parasitology; Mission oriented research; Molecular microbiology; Oxygen requirement; Physiology and metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Sterols; Yeast; Yeasts
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-004-1872-3

Yeasts can incorporate a wide variety of exogenous sterols under strict anaerobiosis. Yeasts normally require oxygen for growth when exogenous sterols are limiting, as this favours the synthesis of lipids (sterols and unsaturated fatty acids). Although much is known about the oxygen requirements of yeasts during anaerobic growth, little is known about their exact sterol requirements in such conditions. We developed a method to determine the amount of ergosterol required for the growth of several yeast strains. We found that pre-cultured yeast strains all contained similar amounts of stored sterols, but exhibited different ergosterol assimilation efficiencies in enological conditions [as measured by the ergosterol concentration required to sustain half the number of generations attributed to ergosterol assimilation (P(50))]. P(50) was correlated with the intensity of sterol synthesis. Active dry yeasts (ADYs) contained less stored sterols than their pre-cultured counterparts and displayed very different ergosterol assimilation efficiencies. We showed that five different batches of the same industrial Saccharomyces cerevisiae ADY exhibited significantly different ergosterol requirements for growth. These differences were mainly attributed to differences in initial sterol reserves. The method described here can therefore be used to quantify indirectly the sterol synthesis abilities of yeast strains and to estimate the size of sterol reserves.