ETHANOL-PRODUCTION FROM ENZYMATIC HYDROLYSATES OF AFEX-TREATED COASTAL BERMUDAGRASS AND SWITCHGRASS

Switchgrass and coastal bermudagrass were pretreated by ammonia fiber explosion (AFEX), and the treated materials hydrolyzed using 5 IU cell ulase/g substrate. Resulting sugar solutions (2-3%, w/v) were fermente d with recombinant Klebsiella oxytoca. Glucose was rapidly and complet ely fermented to ethanol, whereas xylose fermentation was slower and l ess complete. At higher sugar concentrations (similar to 8%) glucose f ermentation continued, but xylose fermentation almost ceased. Protein extraction somewhat enhanced ethanol production from coastal bermudagr ass. Improved fermentation technologies and media appear necessary for practical mixed-sugar lignocellulosic hydrolyzates.