Sucrose is the major carbon source used by S. cerevisiae during production of fuel ethanol, baker's yeast, and several distilled beverages. This yeast cleaves sucrose with an extracellular invertase (encoded by SUC genes), producing glucose and fructose that are taken-up and fermented by the cells. However, attempts to improve sucrose fermentation have failed because high invertase activity is deleterious to yeasts when high sucrose concentrations are used, mainly because the even higher concentrations of glucose plus fructose produced imposes a hyperosmotic shock to the cells. Furthermore, the monosaccharides are excellent carbon sources for other contaminant microorganisms (bacteria and wild yeasts) that can have a detrimental effect on the fermentation process. In the present report we show that a yeast suc^- strain lacking invertase activity, or a strain specifically deleted of the SUC2 gene, ferments sucrose efficiently due to active sucrose uptake through the plasma membrane and intracellular hydrolysis. When compared to industrial strains selected and used for industrial fuel ethanol production, same kinetics of sugar consumption and ethanol production were obtained, with the advantage that no glucose or fructose is detected in the fermentation broth. These strains are currently been tested under industrial conditions to verify their efficiency during fuel ethanol production using high sucrose containing molasses. We further deleted the high-affinity sucrose transporter from the genome of these yeast strains lacking invertase. The engineered strain showed a low-affinity and low-capacity sucrose transport activity. When grown in rich media this strain still exhibited high growth rates, but produced significant lower levels of ethanol, indicating higher oxidative dissimilation of the sucrose present in the medium. When grown in the presence of ammonium sulfate as the sole nitrogen source, significant lower rates of growth were observed, and no ethanol was produced by the cells, while the isogenic strain with high-affinity sucrose transport fermented the sugar normally. Thus, our results indicate an unexpected relationship between the quality of the nitrogen source, and the capacity to ferment sucrose through low-affinity active sugar transport across the plasma membrane.