EXPRESSION OF Saccharomyces cerevisiae α-GLUCOSIDE TRANSPORTERS UNDER DIFFERENT GROWTH CONDITIONS

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.