Selection of Yeast Strain for Ethanol Production from Sugarcane

Abstract

The microbiological fermentation process has great interest for ethanol production and the scientific research, both from a standpoint of productivity and biotechnology. This work was carried out to develop new techniques to reduce costs and improve yield by employing the wild yeast. The aim of this study was select strains with characteristics genetics for ethanol fermentation. After the cells colonies isolated and selectedwere reactivated in a solidmedium and grown in clarified sugarcane juice diluted at 4◦ Brix. After the cell mass obtained, the fermentation tests were carried out in sugar cane juice at 15◦ Brix, at temperature of 28 ◦C, without cells recycling. In this first step 88 yeast strains were analyzed and only 19 were selected, according to their growth and ethanol concentration. In the second step the number of cells was standardized to 108 cells/mL and a new fermentation tests were started in a feed batch process with cells recycling and sugar concentration at 18◦ Brix, temperature of 28 ◦C. The testswere carried out feed batch processwith recycles of yeast cells and 12 hour of fermentation time. Ethanol content, pH, wet and dry cell mass, cell viability, ethanol yield and fermentation efficiency were evaluated in the final fermentation time.