Behaviour of Saccharomyces cerevisiae wine strains during adaptation to unfavourable conditions of fermentation on synthetic medium: Cell lipid composition, membrane integrity, viability and fermentative activity

Ethanol Production and Maximum Cell Growth Are Highly Correlated with Membrane Lipid Composition during Fermentation as Determined by Lipidomic Analysis of 22 Saccharomyces cerevisiae Strains

“…The ergosterol content of ICV K1 (V-1116) never exceeded 5 mol% and was relatively consistent throughout fermentation. It has previously been reported that elevated ergosterol levels are associated with ethanol tolerance in yeast (42,43,51); however, studies involving wine yeast have reported that elevated levels of ergosterol were not critical to the ability to tolerate increasing levels of self-produced ethanol (45,46,52), an observation that was corroborated with this strain and others studied here.…”

“…The lipid membrane bilayer has been shown to be a vulnerable target to the toxic effects of ethanol at both the fundamental level (17)(18)(19)(20)41) and the organismal level (42)(43)(44)(45)(46)(47). In yeast, a number of lipid membrane components have been implicated in ethanol tolerance, including unsaturated fatty acids, er- gosterol, and phospholipid content (42,43,47).…”

Examining the Role of Membrane Lipid Composition in Determining the Ethanol Tolerance of Saccharomyces cerevisiae

“…Strains that were unable to complete fermentation had higher concentrations of phosphatidylinositol during the early stages of fermentation (65). Interestingly, ergosterol was not significantly correlated with ethanol production or yeast cell growth, in agreement with the observations of previous studies analyzing yeast lipid composition during alcoholic fermentation (20,63,64). While it seems likely that ethanol tolerance per cell is related to the biophysical effects discussed here, the reason for the strong correlation between maximum yeast cell density and cell lipid composition is less clear.…”

“…Therefore, they also monitored the lipid composition, membrane integrity, and cell viability throughout the approximately 25-day fermentation. They reported that the strain that utilized the most sugar, produced the highest quantities of ethanol, maintained the lowest membrane permeability, and had the greatest viability exhibited higher C 16 fatty acid-to-total fatty acid (C 16/ TFA) and unsaturated fatty acid-to-total fatty acid (UFA/TFA) levels throughout fermentation (63). They also observed that ergosterol levels were inversely related to the levels of ethanol produced, and they concluded that ergosterol was not essential to cell viability and membrane integrity during alcoholic fermentation.…”

“…Furthermore, none of the investigations discussed here provided structural data on the lipids, which would be critical to understanding how specific lipid species contribute to ethanol tolerance and to elucidate potential mechanisms by which the membrane mitigates the toxic effects of ethanol. Analyses of lipid compositional changes that occur during fermentation in numerous yeast strains with various levels of ethanol tolerance utilizing modern tools of lipidomics and chemometrics are providing much greater insight into how this organism's membrane adapts to ethanol (63)(64)(65). Recently, we developed an analytical methodology utilizing high-performance liquid chromatography coupled online to atmospheric pressure ionization mass spectrometry (API-MS) that facilitates rapid quantitative analysis of yeast lipid extracts (64).…”