Ethanol production from water hyacinth (Eichhornia crassipes) hydrolysate by hyper-thermal acid hydrolysis, enzymatic saccharification and yeasts adapted to high concentration of xylose.

Abstract

Water hyacinth (Eichhornia crassipes) was used as a feedstock for ethanol production. The optimal hyper-thermal (HT) acid hydrolysis conditions were 8% (w/v) slurry content, 200mM H2SO4, at 160°C for 20min and enzymatic saccharification for 48h using an enzyme mixture of 20units/mL Viscozyme L and Cellic C Tec2. After pretreatment, 48.2g/L monosaccharides were obtained. Fermentation was conducted with wild and adapted Saccharomyces cerevisiae, Pichia stipitis and Candida lusitaniae. Wild-type S. cerevisiae, P. stipitis, and C. lusitaniae produced 15.3, 19.5 and 22.7g/L of ethanol, respectively. Adaptive evolution was carried out on 6% (w/v) xylose. S. cerevisiae, P. sipitis and C. lusitaniae adapted to xylose produced 15.3, 21.4 and 23.9g/L of ethanol with YEtOH of 0.32, 0.44 and 0.49, respectively. These results indicate that water hyacinth has potential as a feed stock for ethanol.