ISOLATION AND EVALUATION OF THERMOTOLERANT YEAST STRAINS IN SIMULTANEOUS SACCHARIFICATION AND FERMENTATION OF SUGARCANE BAGASSE

Abstract

The integration of enzymatic hydrolysis and fermentation in one step is known as simultaneous saccharification and fermentation (SSF). A drawback associated with SSF using Saccharomyces cerevisiae is the different optimum temperatures for saccharification and fermentation. The use of organisms with tolerance to high temperatures has to become a necessity. It enables to carry out the SSF at temperatures closed to optimum enzyme temperatures and leads to better conversion of the cellulose and high ethanol yields. As it is known SuperStart yeast, used for ethanol production from corn, has high tolerance to inhibitors. Increasing of thermotolerance is important in order to complete its efficiency for fermentation of cellulosic hydrolyzates to be used in SSF processes. Adaptation by incubation at temperatures up to 40 ⁰C was investigated. Isolated yeast was evaluated in SSF processes. The experiments were carried out at 30 and 38 ⁰C with adapted and non-adapted strains. A high ethanol formation was observed at 38 ⁰C and cellulose conversion was higher in around 4%.