title: Metabolic engineering for improved production of ethanol by Corynebacterium glutamicum.
abstract: Recombinant Corynebacterium glutamicum harboring genes for pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adhB) can produce ethanol under oxygen deprivation. We investigated the effects of elevating the expression levels of glycolytic genes, as well as pdc and adhB, on ethanol production. Overexpression of four glycolytic genes (pgi, pfkA, gapA, and pyk) in C. glutamicum significantly increased the rate of ethanol production. Overexpression of tpi, encoding triosephosphate isomerase, further enhanced productivity. Elevated expression of pdc and adhB increased ethanol yield, but not the rate of production. Fed-batch fermentation using an optimized strain resulted in ethanol production of 119 g/L from 245 g/L glucose with a yield of 95% of the theoretical maximum. Further metabolic engineering, including integration of the genes for xylose and arabinose metabolism, enabled consumption of glucose, xylose, and arabinose, and ethanol production (83 g/L) at a yield of 90 %. This study demonstrated that C. glutamicum has significant potential for the production of cellulosic ethanol.
authors.affiliation: Research Institute of Innovative Technology for the Earth, 9-2, Kizugawadai, Kizugawa, Kyoto, 619-0292, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Jojima
authors.forename: Ryoji
authors.initials: R
authors.lastname: Noburyu
authors.forename: Miho
authors.initials: M
authors.lastname: Sasaki
authors.forename: Takahisa
authors.initials: T
authors.lastname: Tajima
authors.forename: Masako
authors.initials: M
authors.lastname: Suda
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yukawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Inui
mesh_terms: D061249:Batch Cell Culture Techniques; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D015870:Gene Expression; D005798:Genes, Bacterial; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000235:genetics
chemical_list: D000431:Ethanol