Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
Ethanol production by recombinant Saccharomyces cerevisiae in pretreated barley straw was examined. Because barley straw was burned on site after harvesting and causes air pollution, it could be obtained as byproduct from agriculture and promise for use as feedstock for the production of fermentable sugars. Barely straw requires pretreatment to facilitate the release of sugars from a biomass prior to fermentation. We applied the Ammonia Fiber Explosion (AFEX) process which treats lignocellulose with high-pressure liquid ammonia (15%) at 150°C for 90 min causing cellulose to decrystallize and then explosively releases the pressure. The use of AFEX process exhibited that 28.3% of the lignin was solubilized with 50.1% of glucose and 5.9% of xylose being sugar monomers. The ethanol fermentation was carried using recombinant S. cerevisiae which are able to express beta-glucosidase from Saccharomycopsis fibuligera and cellulases from Clostridium spp. (C. thermocellum and C. cellulovorans). In the fermentation of biomass, approximately 2.45 g/L ethanol was produced from 10 g/L barley straw and it was three times higher than that in wild-type stain. The results showed that high ethanol productivity was achieved at expressing both of beta-glucosidase and endoglucanase and it was concluded that recombinant S. cerevisiae is very suitable for industrial ethanol production from pretreated biomass.