Influence of stressful fermentation conditions on neutral lipids of a Saccharomyces cerevisiae brewing strain

Abstract

The neutral lipid fraction of the aerobically grown starter yeast culture of a Saccharomyces cerevisiae brewing strain, and three-first recycled yeast generations exposed to multiple stress factors during beer fermentation was studied. No pronounced changes in the cellular neutral lipid content between the non-stressed starter and stressed recycled cells were found. However, it was found that recycled yeast generations modulate their neutral lipid composition during fermentation. The ergosterol content was increased at the expense of steryl esters (SEs) and squalene, which resulted in a higher ergosterol/SEs molar ratio and a slightly higher ergosterol/squalene molar ratio. In addition, the proportion of unsaturated fatty acids, mainly palmitoleic acid increased in the neutral lipid fraction of the stressed recycled yeast generations. These results suggest that some specific neutral lipid species and fatty acids stored in the neutral lipid fraction are involved in the adaptive response of the brewer's yeast to stressful fermentation conditions. The striking finding was a high squalene content in the neutral lipid fraction of both the starter yeast culture and recycled yeast generations (22.4 vs. 19-20%, respectively), implying a possible biotechnological exploitation of this biologically active molecule from the yeast biomass.

Effects of Adding Unsaturated Fatty Acids on Fatty Acid Composition of Saccharomyces cerevisiae and Major Volatile Compounds in Wine

“…This can be ascribed to the fact that fatty acid desaturation cannot occur in yeast cells under anaerobic conditions (Snoek & Steensma, 2007). Our results demonstrate that the enrichment of UFAs in cells is essential for yeast adaptation to environmental stress during alcoholic fermentation (You et al, 2003;Rupčić & Jurešić, 2010).…”

“…They are essential not only for maintaining membrane integrity and function, but also for adapting to fermentation stresses, such as high sugar and ethanol toxicity (Holcberg & Margalith, 1981;You et al, 2003;Rupčić & Jurešić, 2010). A higher degree of unsaturation of the cell membrane can maintain higher membrane fluidity and guarantee the activity of membrane-associated enzymes and transporters, such as ATPase and general amino acid permease (GAP) (Calderbank et al, 1985;Rosa & SaCorreia, 1992).…”

Waste Brewery and Winery Yeast as a Raw Material for Biotechnological Productions

“…V anaerobní kultuře může při nedostatku kyslíku dojít k zablokování biosyntézy a následné reakci Δ 9 desaturasy a skvalen-epoxidasy, což může vést, zejména při výrobě piva v cylindrokónických tancích, ke zvýšené akumulaci nasycených mastných kyselin nebo ke zvýšené produkci prekurzorů ergosterolu (Rupčić et al, 2010). Fermentační teplota má významný vliv na produkci palmitolejové kyseliny.…”

“…In an anaerobic culture with oxygen defi ciency, its biosynthesis can be blocked and subsequent reaction of Δ 9 desaturase and squalene epoxidase can lead, in particular in beer production in cylindro-conical fermentors, to increased accumulation of saturated fatty acids or increased production of ergosterol precursors (Rupčić et al, 2010). The fermentation temperature also has a signifi cant effect on the production of palmitoleic acid.…”

Effect of Environmental Stress Factors and Recycling on the Lipid Composition of Brewer’s Yeast Mitochondria

“…We have published data on the lipid composition of the bottom-fermenting brewer's yeast obtained in the industrial process of beer production in another brewing company, its cells and organelles 19,20 and data on the alterations of several lipid parameters caused by recycling of the yeast analysed in this study. [21][22][23] In the present study, we analysed the alterations in the lipid composition of the mitochondria, which occur during propagation, brewing and repetitive recycling of the yeast biomass. The results provide a better insight into the capability of brewer's yeast to adapt to stress conditions because each of the three phases the brewer's yeast passes through during beer production (propagation, fermentation and storage) and also the transition from one phase to another, include a number of stresses.…”