title: Improvement of ethanol yield from glycerol via conversion of pyruvate to ethanol in metabolically engineered Saccharomyces cerevisiae.
abstract: The conversion of low-priced glycerol to higher value products has been proposed as a way to improve the economic viability of the biofuels industry. In a previous study, the conversion of glycerol to ethanol in a metabolically engineered strain of Saccharomyces cerevisiae was accomplished by minimizing the synthesis of glycerol, the main by-product in ethanol fermentation processing. To further improve ethanol production, overexpression of the native genes involved in conversion of pyruvate to ethanol in S. cerevisiae was successfully accomplished. The overexpression of an alcohol dehydrogenase (adh1) and a pyruvate decarboxylase (pdc1) caused an increase in growth rate and glycerol consumption under fermentative conditions, which led to a slight increase of the final ethanol yield. The overall expression of the adh1 and pdc1 genes in the modified strains, combined with the lack of the fps1 and gpd2 genes, resulted in a 1.4-fold increase (about 5.4 g/L ethanol produced) in fps1Δgpd2Δ (pGcyaDak, pGupCas) (about 4.0 g/L ethanol produced). In summary, it is possible to improve the ethanol yield by overexpression of the genes involved in the conversion of pyruvate to ethanol in engineered S. cerevisiae using glycerol as substrate.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Kyung Ok
authors.initials: KO
authors.lastname: Yu
authors.forename: Ju
authors.initials: J
authors.lastname: Jung
authors.forename: Ahmad Bazli
authors.initials: AB
authors.lastname: Ramzi
authors.forename: Seung Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Chulhwan
authors.initials: C
authors.lastname: Park
authors.forename: Sung Ok
authors.initials: SO
authors.lastname: Han
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D019149:Bioreactors; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D015870:Gene Expression; D005990:Glycerol / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods; D010957:Plasmids; D011767:Pyruvate Decarboxylase / Q000235:genetics* / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D019289:Pyruvic Acid; D000426:Alcohol Dehydrogenase; D011767:Pyruvate Decarboxylase; D005990:Glycerol