Ethanol production from hemicellulose by a consortium of different genetically-modified sacharomyces cerevisiae

Abstract

Abstract In this study, Saccharomyces cerevisiae was engineered to degrade and utilize xylan, one of the major polysaccharide chains present in hemicellulose. Different hemicellulases from Trichoderma reesei, namely: endoxylanase, β-xylosidase, acetylxylan esterase, α- d -glucuronidase and α- l -arabinofuranosidase, were heterologously secreted by S. cerevisiae. A mixture experimental design was adapted to statistically describe the synergistic interactions between the hemicellulases and to determine the optimum formulations for the hydrolysis of xylan substrates. The hydrolytic activities of the hemicellulase mixtures were then improved by displaying the hemicellulases on the yeast surface as whole-cell biocatalysts. The engineered yeast strains displaying hemicellulases were further engineered to express xylose-utilization genes xylose isomerase (XI) and xylulokinase (XK) which enable its utilization of xylose as a sole carbon source. The resulting consortium was then able to grow and produce ethanol from different xylan substrates.