Changes in lipid metabolism convey acid tolerance in Saccharomyces cerevisiae

Abstract

BackgroundThe yeast Saccharomyces cerevisiae plays an essential role in the fermentation of lignocellulosic hydrolysates. Weak organic acids in lignocellulosic hydrolysate can hamper the use of this renewable resource for fuel and chemical production. Plasma-membrane remodeling has recently been found to be involved in acquiring tolerance to organic acids, but the mechanisms responsible remain largely unknown. Therefore, it is essential to understand the underlying mechanisms of acid tolerance of S. cerevisiae for developing robust industrial strains.ResultsWe have performed a comparative analysis of lipids and fatty acids in S. cerevisiae grown in the presence of four different weak acids. The general response of the yeast to acid stress was found to be the accumulation of triacylglycerols and the degradation of steryl esters. In addition, a decrease in phosphatidic acid, phosphatidylcholine, phosphatidylserine and phosphatidylethanolamine, and an increase in phosphatidylinositol were observed. Loss of cardiolipin in the mitochondria membrane may be responsible for the dysfunction of mitochondria and the dramatic decrease in the rate of respiration of S. cerevisiae under acid stress. Interestingly, the accumulation of ergosterol was found to be a protective mechanism of yeast exposed to organic acids, and the ERG1 gene in ergosterol biosynthesis played a key in ergosterol-mediated acid tolerance, as perturbing the expression of this gene caused rapid loss of viability. Interestingly, overexpressing OLE1 resulted in the increased levels of oleic acid (18:1n-9) and an increase in the unsaturation index of fatty acids in the plasma membrane, resulting in higher tolerance to acetic, formic and levulinic acid, while this change was found to be detrimental to cells exposed to lipophilic cinnamic acid.ConclusionsComparison of lipid profiles revealed different remodeling of lipids, FAs and the unsaturation index of the FAs in the cell membrane in response of S. cerevisiae to acetic, formic, levulinic and cinnamic acid, depending on the properties of the acid. In future work, it will be necessary to combine lipidome and transcriptome analysis to gain a better understanding of the underlying regulation network and interactions between central carbon metabolism (e.g., glycolysis, TCA cycle) and lipid biosynthesis.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1295-5) contains supplementary material, which is available to authorized users.

Genome-Wide Identification of Genes Involved in General Acid Stress and Fluoride Toxicity in Saccharomyces cerevisiae

“…During acidosis, fungi lower metabolism and protein synthesis, and increase the production of saturated lipids and ergosterol to adjust membrane fluidity (Sousa et al, 2012;Brandao et al, 2014;Guo and Olsson, 2016;Godinho et al, 2018;Palma et al, 2018). Cells also undergo remodeling of their plasma membranes and cytoskeletal components (Mollapour et al, 2006;Guo et al, 2018). While these are general response mechanisms to acidosis, different acids often elicit unique stress phenotypes based on their given properties.…”

Cellular mechanism for the improvement of multiple stress tolerance in brewer's yeast by potassium ion supplementation

“…Ergosterol plays an important role in maintaining yeast cell membrane stabilisation and has a close relationship with membrane proteins (Patricia et al , ; Hu et al , ). High content of ergosterol in yeast could promote yeast growth in the presence of multiple stresses (Guo et al , ; Fu et al , ). Ergosterol contents of yeast in the medium with different concentrations of KCl were analysed, and the results are shown in Fig.…”

Effect of Lactic Acid Bacteria and Yeasts towards Chemical, Physical and Organoleptic Qualities of Mutton Salami

“…The increasing levels of yeast and LAB have no significant effect on the fat content, due to the fat degradation by lipase enzymes in salami and producing a group of free fatty acids that give the characteristic such as taste, odor and the structure which depends on the type of acid. Degradation of phospholipids may change the structure of lipids in meal or food, although lipid metabolism by yeasts includes lipase lipid production outside the cells [18].…”

“…The activity of LAB could decline pH and yielding several compounds such as hydrogen peroxide, diacetyl, carbon dioxide, and a bacteriocin. Lactic acid bacteria are a group of gram-positive bacteria that not created spores, have coccus and stem forms, and can ferment carbohydrates to produce lactic acid [3].…”