Genotypic Variation in Ethanolic Fermentation Using New Genetically Recombinants of Saccharomyces cerevisiae

Abstract

This study aimed to investigate metabolic changed related to glucoserepression by the analysis of ethanol productivity which is mainly affected by the glucose effect. Five parental isolates and 15 genotypes derived from three crosses were used in this study to be evaluated for heterosis of ethanol productivity. Bioethanol produced can contribute to a cleaner environment using a cheap substrates such as sugarcane juice subproducts used in this study. Mating between yeast isolates gave different recombinant genotypes some of them showed glucoserepressed or depressed to higher concentrations of sugarcane juice subproducts. Sugar repression is one of the major limitations in the fermentation of costeffective ethanol productivity. When the hybrid genotypes were grown in a culture containing 0.02 subproducts they are exhibited positive hybrid vigor for ethanol production overall the genotypes compared to the midparents. All hybrids exhibited negative heterosis when they were cultivated in the culture containing 0.04 subproducts, indicating that they were glucosesensitive due to glucose pulses at this concentration. In addition, when the hybrids resulted from the cross between p1 x p4 were grown in a fermentation culture containing 0.06 subproducts they are also exhibited negative heterosis for ethanol productivity. In contrast, all the hybrids derived from the crosses between p2 x p5 and p3 x p5 overcoming glucose repression of 0.06 subproducts containing medium because heterosis seemed to appear at this level of carbohydrates.