Production of ethanol from steam exploded triticale straw in a simultaneous saccharification and fermentation process

Abstract

Abstract The cost-effective production of bioethanol requires an inexpensive feedstock that is easily hydrolysed by minimal amounts of cellulase enzymes and efficiently converted to ethanol. Steam-exploded triticale straw was investigated for ethanol production using selected commercial cellulases, with Spezyme® CP outperforming the other enzymes in terms of glucose release. Varying enzyme dosages (5, 10 and 15 FPU Spezyme® CP/g cellulose) and different solids loadings (5, 10 and 15% w/v) were evaluated in simultaneous saccarification and fermentation (SSF) experiments with Saccharomyces cerevisiae Ethanol Red® as fermenting yeast. A 15% (w/v) solids loading with 15 FPU Spezyme® CP/g cellulose produced 29.6 g/l ethanol (81.3% ethanol yield). When the high-gravity SSF was repeated in a 1-l bioreactor using 15% solids and 15 FPU Spezyme® CP/g cellulose, an ethanol concentration of 29.31 g/l (84.7% ethanol yield) was achieved after 144 h without additional β-glucosidase. Similar results have been observed by other researchers, but with higher enzyme dosages or the addition of β‐glucosidase or xylanase. This study demonstrates that triticale straw is a potential feedstock for the production of lignocellulosic bio-ethanol, and further optimisation of the SSF conditions could result in a commercially viable process for the production of bio-ethanol.