Improvement of Brazilian bioethanol production - Challenges and perspectives on the identification and genetic modification of new strains of Saccharomyces cerevisiae yeasts isolated during ethanol process.

In Brazil, bioethanol is produced by sucrose fermentation from sugarcane by Saccharomyces cerevisiae in a fed-batch process that uses high density of yeast cells (15-25 % of wet weight/v) and high sugar concentration (18-22 % of total sugars). Several research efforts have been employed to improve the efficiency of this process through the isolation of yeasts better adapted to the Brazilian fermentation conditions. Two important wild strains named CAT-1 and PE-2 were isolated during the fermentation process and were responsible for almost 60 % of the total ethanol production in Brazil.