Effects of ethanol and other alkanols on the glucose transport system of Saccharomyces cerevisiae

Effects of alcohols on the respiration and fermentation of aerated suspensions of baker's yeast

“…These include alteration of membrane permeability properties, sugar transport systems, direct effects on enzymes, product inhibition or accumulation of toxic metabolites (Leao & Van Uden, 1982;Ingram & Buttke, 1984;Casey & Ingledew, 1986;Jones & Greenfield, 1987;Jones, 1989;Koukou et al, 1990 ;D'Amore & Stewart, 1990). These various proposals are not mutually exclusive, and different inhibitory effects may assume greater or lesser significance in different yeasts and under different environmental situations.…”

“…The inhibition pattern is noncompetitive, ethanol decreasing the maximal uptake rate. The correlation found between the hydrophobicity and ability of alkanols to inhibit glucose utilization (Gray & Sova, 1956;Ingram & Buttke, 1984) and glucose uptake (Leao & Van Uden, 1982) seems to indicate a membrane effect. Yeast grown in the presence of increasing concentrations of ethanol has also been shown to increase the content of mono-unsaturated fatty acids in its membrane lipids in response (Beavan et al, 1982).…”

Effect of ethanol on the fructose transport system of Kluyveromyces fragilis

“…cerevisiae (Leao and van Uden, 1982b), the ef---fects of ethanol on the fructose transport system of K. fra@ilis over the range of concentrations tested may be expressed by the following equation v = V 0 e -kx S (i) max K +S m where S is the concentration of D-xylose, fructose or any other sugar that uses the same transport system; V0ma x is the ma~ uptake rate without ethanol; x is the ethanol concentration; k is the exponential ethanol inhibition constant.…”

“…cerev{8£ae, transport of glucose (Leao and van Uden, 1982b) and of maltose (Loureiro-Dias and Peinado, 1982) are inhibited in a non-competitive way, by ethanol and other alkanols.…”

“…These measurements were executed as described by Leao and van Uden, 1982b. In i0 ml conical centrifuge tubes 20 ~i of the cell suspension and 20 ul of tris citrate buffer 0.01 M pH 4.5 containing ethanol at the desi~d concentration were mixed. After 5 minutes' equilibration at 25 C, the reaction was started by the addition of i0 ~I of an aqueous solution of [U-14C]D-xylose at the desired concentration and stopped by the addition of l0 ml of ice-cold water.…”