Evaluation of pretreated herbaceous crops for the simultaneous saccharification and fermentation process

Abstract

Three dilute acid pretreated herbaceous crops (Weeping lovegrass,Eragrotis curvula; Sericea lespedeza,Lespedeza cuneata; and switch-grass,Panicum virgatum) were evaluated in the simultaneous saccharification and fermentation (SSF) process for ethanol production with selected yeast strains and enzyme combinations.Saccharomyces cerevisiae (D5A) was used in the fermentations as a single culture and in a mixed culture with β-glucosidase, producingBrettanomyces clausenii Y-1414. Cellulase enzyme was either employed alone or in combination with β-glucosidase. SSF’s were run at 37°C for 8 d along with a saccharification study at 45°C under similar enzyme loadings. Both cultures achieved high ethanol yields and rates of hydrolysis at the higher enzyme loadings, and the mixed culture shows improvement over S.cerevisiae for the lower enzyme loadings without β-glucosidase supplementation. Of the three herbaceous crops tested, Weeping lovegrass excels in both rate and final ethanol yields, followed closely by Switchgrass, whereas the legume(Sericea lespedeza) trailed behind both grasses in conversion performance.