Diluted acid pretreatment of pinus radiata for bioethanol production using immobilized saccharomyces cerevisiae IR2-9 in a simultaneous saccharification and fermentation process

Abstract

The production of bioethanol from pretreated lignocellulosic materials requires the utilization of microorganisms adapted to ferment the materials in conditions were high consistency, temperatures and inhibitors concentrations were commonly found. The yeast immobilization in calcium alginate capsules has been reported to enhance the yeast protection and increase the efficiency in the fermentation process. In this work, it was investigated the use Saccharomyces cerevisiae immobilized in calcium alginate and its performance in simultaneous saccharification and fermentation (SSF) of diluted-acid-pretreated Pinus radiata. Results showed that when immobilized yeast was used, the bioethanol yield from pretreated wood was higher than with free yeast cells during a SSF process. Maximum ethanol yield obtained from the acid pretreated and milled wood chips was 153 L/ton wood, while from the hydrolysate fraction it was 18 L/ton wood. The sum of ethanol produced from dilute acid pretreated P. radiata for both solid and liquid fractions was 171 L ethanol/ton wood from a maximum theoretical of 236 L/ton pretretated wood (or 72% of conversion).