title: Lactose fermentation by engineered Saccharomyces cerevisiae capable of fermenting cellobiose.
abstract: Lactose is an inevitable byproduct of the dairy industry. In addition to cheese manufacturing, the growing Greek yogurt industry generates excess acid whey, which contains lactose. Therefore, rapid and efficient conversion of lactose to fuels and chemicals would be useful for recycling the otherwise harmful acid whey. Saccharomyces cerevisiae, a popular metabolic engineering host, cannot natively utilize lactose. However, we discovered that an engineered S. cerevisiae strain (EJ2) capable of fermenting cellobiose can also ferment lactose. This finding suggests that a cellobiose transporter (CDT-1) can transport lactose and a β-glucosidase (GH1-1) can hydrolyze lactose by acting as a β-galactosidase. While the lactose fermentation by the EJ2 strain was much slower than the cellobiose fermentation, a faster lactose-fermenting strain (EJ2e8) was obtained through serial subcultures on lactose. The EJ2e8 strain fermented lactose with a consumption rate of 2.16g/Lh. The improved lactose fermentation by the EJ2e8 strain was due to the increased copy number of cdt-1 and gh1-1 genes. Looking ahead, the EJ2e8 strain could be exploited for the production of other non-ethanol fuels and chemicals from lactose through further metabolic engineering.
authors.affiliation: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL 61801, United States.
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Liu
authors.affiliation: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL 61801, United States; Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, United States.
authors.forename: Guo-Chang
authors.initials: GC
authors.lastname: Zhang
authors.affiliation: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL 61801, United States; Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, United States.
authors.forename: Eun Joong
authors.initials: EJ
authors.lastname: Oh
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, United States.
authors.forename: Panchalee
authors.initials: P
authors.lastname: Pathanibul
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, United States.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Turner
authors.affiliation: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL 61801, United States; Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, United States. Electronic address: ysjin@illinois.edu.
authors.forename: Yong-Su
authors.initials: YS
authors.lastname: Jin
mesh_terms: D002475:Cellobiose / Q000737:chemistry / Q000378:metabolism; D056915:DNA Copy Number Variations; D004789:Enzyme Activation; D000431:Ethanol / Q000737:chemistry / Q000378:metabolism; D005285:Fermentation; D007785:Lactose / Q000737:chemistry / Q000378:metabolism*; D060847:Metabolic Engineering; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D002475:Cellobiose; D000431:Ethanol; D001617:beta-Glucosidase; D001616:beta-Galactosidase; D007785:Lactose
keywords: Adaptive evolution; Lactose fermentation; Saccharomyces cerevisiae; cdt-1; gh1-1