title: Xylitol production by genetically engineered Trichoderma reesei strains using barley straw as feedstock.
abstract: Xylitol, a naturally occurring five-carbon sugar alcohol derived from D-xylose, is currently in high demand by industries. Trichoderma reesei, a prolific industrial cellulase and hemicellulase producing fungus, is able to selectively use D-xylose from hemicelluloses for xylitol production. The xylitol production by T. reesei can be enhanced by genetic engineering of blocking further xylitol metabolism in the D-xylose pathway. We have used two different T. reesei strains which are impaired in the further metabolism of xylitol including a single mutant in which the xylitol dehydrogenase gene was deleted (∆xdh1) and a double mutant where additionally L-arabinitol-4-dehydrogenase, an enzyme which can partially compensate for xylitol dehydrogenase function, was deleted (∆lad1∆xdh1). Barely straw was first pretreated using NaOH and Organosolv pretreatment methods. The highest xylitol production of 6.1 and 13.22 g/L was obtained using medium supplemented with 2 % Organosolv-pretreated barley straw and 2 % D-xylose by the ∆xdh1 and ∆lad1∆xdh1 strains, respectively.
authors.affiliation: Biorefining Research Institute (BRI), Lakehead University, 955 Oliver Road, Thunder Bay, ON, Canada P7E 5E1. mdashtba@lakeheadu.ca
authors.forename: Mehdi
authors.initials: M
authors.lastname: Dashtban
authors.forename: Greg
authors.initials: G
authors.lastname: Kepka
authors.forename: Bernhard
authors.initials: B
authors.lastname: Seiboth
authors.forename: Wensheng
authors.initials: W
authors.lastname: Qin
mesh_terms: D050542:D-Xylulose Reductase / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D024861:Genetic Enhancement / Q000379:methods*; D001467:Hordeum / Q000382:microbiology*; D009154:Mutation; D035261:Plant Components, Aerial / Q000382:microbiology*; D013045:Species Specificity; D014242:Trichoderma / Q000201:enzymology* / Q000235:genetics*; D014993:Xylitol / Q000096:biosynthesis* / Q000302:isolation & purification
chemical_list: D050542:D-Xylulose Reductase; D014993:Xylitol