title: Ethanol production from wood hydrolysate using genetically engineered Zymomonas mobilis.
abstract: An ethanologenic microorganism capable of fermenting all of the sugars released from lignocellulosic biomass through a saccharification process is essential for secondary bioethanol production. We therefore genetically engineered the ethanologenic bacterium Zymomonas mobilis such that it efficiently produced bioethanol from the hydrolysate of wood biomass containing glucose, mannose, and xylose as major sugar components. This was accomplished by introducing genes encoding mannose and xylose catabolic enzymes from Escherichia coli. Integration of E. coli manA into Z. mobilis chromosomal DNA conferred the ability to co-ferment mannose and glucose, producing 91 % of the theoretical yield of ethanol within 36 h. Then, by introducing a recombinant plasmid harboring the genes encoding E. coli xylA, xylB, tal, and tktA, we broadened the range of fermentable sugar substrates for Z. mobilis to include mannose and xylose as well as glucose. The resultant strain was able to ferment a mixture of 20 g/l glucose, 20 g/l mannose, and 20 g/l xylose as major sugar components of wood hydrolysate within 72 h, producing 89.8 % of the theoretical yield. The recombinant Z. mobilis also efficiently fermented actual acid hydrolysate prepared from cellulosic feedstock containing glucose, mannose, and xylose. Moreover, a reactor packed with the strain continuously produced ethanol from acid hydrolysate of wood biomass from coniferous trees for 10 days without accumulation of residual sugars. Ethanol productivity was at 10.27 g/l h at a dilution rate of 0.25 h(-1).
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyamacho-Minami, Tottori, Tottori 680-8552, Japan. yanase@bio.tottori-u.ac.jp
authors.forename: Hideshi
authors.initials: H
authors.lastname: Yanase
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Miyawaki
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Sakurai
authors.forename: Akinori
authors.initials: A
authors.lastname: Kawakami
authors.forename: Mari
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Haga
authors.forename: Motoki
authors.initials: M
authors.lastname: Kojima
authors.forename: Kenji
authors.initials: K
authors.lastname: Okamoto
mesh_terms: D002482:Cellulose / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005818:Genetic Engineering; D005947:Glucose / Q000378:metabolism; D006868:Hydrolysis; D008358:Mannose / Q000378:metabolism; D014934:Wood / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology*; D014994:Xylose / Q000378:metabolism; D017355:Zymomonas / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000431:Ethanol; D002482:Cellulose; D014994:Xylose; D005947:Glucose; D008358:Mannose