The production of ethanol from cellulosic biomass hydrolysates using S. cerevisiae 424A(LNH-ST) and its ethanol resistant (424A(LNH-ST)-ER) and acetic acid resistant (424A(LNH-ST)-AR) variants

Cellulosic biomass of lignocellulosic feedstocks is renewable, available at low cost, and exists in great abundance all over the world. The efficient fermentation of xylose-rich hemicellulose hydrolysates represents an opportunity to significantly improve the economics of large-scale fuel ethanol production from lignocellulosic feedstocks. Currently our best engineered yeast, known as 424A(LNH-ST), has already been used by industry to produce cellulosic ethanol.       

      Recently we developed two derivatives of 424A(LNH-ST), one resistant to acetic acid (424A(LNH-ST)-AR) and the other resistant to ethanol (424A(LNH-ST)-ER) that can ferment xylose even more efficiently. The specific xylose fermenting rates for these new strains were observed to be at least two times higher compared to the original strain.

      In this report we investigated the fermentability of the cellulosic hydrolysates prepared from different sources – corn stover, wood, Arundo sp., sugarcane bagasse etc. The sugar concentrations in these hydrolysates ranged from 7 – 240 g/L for glucose and 30 – 80 g/L for xylose. Our genetically engineered glucose/xylose co-fermenting Saccharomyces yeasts 424A(LNH-ST), 424A(LNH-ST)-ER, and 424A(LNH-ST)-AR were used for fermentation. Our results show that our yeast efficiently ferment cellulosic hydrolysates prepared from various cellulosic biomass. This presentation will also discuss the use of our yeast in ethanol production from corn mash.