Effects of the carbon source and the interaction between carbon sources on the physiology of the industrial Saccharomyces cerevisiae CAT-1

Abstract

During industrial fermentation, wild isolates are able to persist and even predominate in the bioreactors. Saccharomyces cerevisiae CAT-1 was one of these isolates and now is one of the yeasts mostly used in industrial ethanol processes in Brazil due to its efficient fermentation capacity. Despite it, the strain’s physiology has been marginally studied so far. Since strains of the same species may have different responses to a specific cultivation condition, this work aimed to evaluate the physiology of S. cerevisiae CAT-1 in batch cultures using different carbon sources (glucose, fructose, sucrose, maltose, and galactose) as a sole carbon source and in binary mixtures, at 30 and 37?°C. The results showed that the fructose, sucrose, and maltose were the sugars that presented the highest ethanol yields on the substrate (0.40?g_ethanol g_substrate^?1) at both temperatures. Galactose was the sugar that the yeast had the lowest affinity given the lowest maximum specific growth rate (0.28?h^?1). Despite the influence of a variety of mechanisms for sugar transport, the cells consume first substrates with fewer metabolic steps to catabolism and are susceptible to adaptive evolution depending on the availability of substrate.