Expression of Saccharomyces cerevisiae α-glucoside transporters under different growth conditions

Abstract

-Important biotechnological processes depend on the efficient fermentation by Saccharomyces cerevisiae yeasts of starch hydrolysates rich in maltose and maltotriose. The rate-limiting step for fermentation of these α-glucosides is the transport across the plasma membrane of the cells. In order to contribute to a better understanding of maltose and maltotriose metabolism by S. cerevisiae, we analyzed the expression of the main α -glucoside transporter genes in two different yeast strains grown on media with glucose, maltose or maltotriose as carbon source. Although both yeast strains have higher α-glucoside transport activity during growth on maltotriose, our results show similar expression levels of the analyzed genes on either maltose or maltrotriose media. Thus, our results indicate that, although the transport capacity of maltotriose grown cells is higher than that of maltose grown cells, maltotriose cannot be considered a better inducer of α-glucoside transporter genes.

ETHANOL PRODUCTION FROM SUGAR LIBERATED FROM Pinus SP. AND Eucalyptus SP. BIOMASS PRETREATED BY IONIC LIQUIDS

“…The most widely used microorganism for alcoholic fermentation is Saccharomyces cerevisiae (Alves Jr et al, 2014), due to its ability to hydrolyze sucrose into glucose and fructose, two easily assimilated hexoses. Other yeasts, such as Schizosaccharomyces pombe, have the additional advantage of tolerating high osmotic pressure (large amounts of salts) and high percentage of solids (Sánchez & Cardona, 2008 (Schneider et al, 2016) using S. cerevisiae and S. pombe Y-698 yeasts for alcoholic fermentation.…”

Extracellular maltotriose hydrolysis bySaccharomyces cerevisiaecells lacking theAGT1permease

“…The MAL1 locus is probably the progenitor locus from which all other MAL loci were derived, as all S. cerevisiae strains and other Saccharomyces yeasts contain MAL1 sequences. This pattern holds true even for many nonmaltose/maltotriose-fermenting yeast strains, which may harbour partially functional mal1p (MAL13 mal11 mal12), mal1g (mal13 MAL11 MAL12), or mal1 0 (mal13 mal11 MAL12) loci (Naumov et al 1994;Han et al 1995;Alves et al 2007Alves et al , 2014.…”