Genetically modified yeast species and fermenation processes using genetically modified yeast
AssigneeCargill, Incorporated
InventorsVineet Rajgarhia, Kari Koivuranta, Merja Penttilä, Marja Ilmen, Pirkko Suominen, Aristos Aristidou, Christopher Miller, Stacey Olson, Laura Ruohonen
Life of this patent
Estimating the term…
Abstract
Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications', include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.
Claims84
A genetically modified yeast cell of the genera Kluyveromyces, Candida, Pichia, Brettanomyces or Pachysolen having a genome and a functional, exogenous xylose isomerase gene, wherein the exogenous xylose isomerase gene is operatively linked to promoter and terminator sequences that are functional in the yeast cell, and the modified yeast cell further has a deletion or disruption of a native gene that produces an enzyme that catalyzes the conversion of xylose to xylitol.
A genetically modified yeast cell having a genome and a functional, exogenous xylose isomerase gene, wherein the exogenous xylose isomerase gene is operatively linked to promoter and terminator sequences that are functional in the yeast cell, and the modified yeast cell further has a deletion or disruption of a native gene that produces an enzyme that is specific to the conversion of xylose to xylitol.
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18-20. (canceled)
A genetically modified yeast cell of the genera Kluyveromyces, having integrated into its genome a functional, exogenous xylose isomerase gene, wherein the exogenous xylose isomerase gene is operatively linked to promoter and terminator sequences that are functional in the yeast cell.
A genetically modified yeast cell of the genera Kluyveromyces, Candida, Pichia, Brettanomyces or Pachysolen having a genome and a functional, exogenous xylose isomerase gene, wherein the exogenous xylose isomerase gene is operatively linked to promoter and terminator sequences that are functional in the yeast cell, and which further contains a functional, exogenous xylulokinase gene operatively linked to promoter and terminator sequences that are functional in the yeast cell.
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A genetically modified yeast cell having a deletion or disruption of a functional, native gene that produces an enzyme that catalyzes the reaction of xylitol to xylulose or of xylulose to xylitol.
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32-33. (canceled)
A genetically modified yeast cell having a deletion or disruption of a native xylitol dehydrogenase gene that produces an enzyme that is specific to the conversion of xylose to xylitol, the cell further having a deletion or disruption of a native gene that produces an enzyme that catalyzes the conversion of xylulose to xylitol.
37-39. (canceled)
The genetically modified yeast cell of wherein the yeast cell is K. marxianus.
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A vector for transforming a host yeast cell, comprising, in order of transcription, an upstream (5′-) region of a xylose reductase gene of the host cell, a selection marker expression cassette, and a downstream (3′-) region of a xylose reductase gene of the host cell.
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62-63. (canceled)
A vector for transforming a host yeast cell, comprising, in order of transcription, an upstream (5′-) region of a xylitol dehydrogenase gene of the host cell, a selection marker expression cassette, and a downstream (3′-) region of a xylose dehydrogenase gene of the host cell.
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A vector for transforming a host yeast cell comprising a HisG-Ura3-HisG cassette, and a xylose isomerase expression cassette, a xylulokinase expression cassette or both a xylose isomerase expression cassette and a xylulokinase expression cassette.
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A genetically modified yeast cell having a functional, exogenous xylose isomerase gene integrated into its genome, which cell has a xylose reductase activity of no greater than 10 mU/mg.
A genetically modified yeast cell having a functional, exogenous xylose isomerase gene integrated into its genome, which cell has a xylitol dehydrogenase activity of no greater than 2 mU/mg.
A genetically modified yeast cell having a functional, exogenous xylose isomerase gene integrated into its genome, which cell has a xylulokinase activity of at least 100 mU/mg.
A method of evaluating xylose isomerase genes for activity in a host cell, comprising transforming a host cell having low aldose reductase enzyme activity, low xylitol dehydrogenase enzyme activity and overexpressed xylulokinase enzyme activity, with a vector containing the xylose isomerase gene under the control of promoter and terminator which are active in the host cell, selecting for transformed cells containing the xylose isomerase gene, and determining the activity of an enzyme encoded by the xylose isomerase gene in the host cell.
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Dependencies are inferred from the claim text.