Transgenic plants containing ligninase and cellulase which degrade lignin and cellulose to fermentable sugars
First Claim
1. A transgenic herbaceous plant which degrades lignocellulose when the transgenic plant is ground to produce a plant material comprising:
- (a) at least one DNA encoding a microbial cellulase which is operably linked to a nucleotide sequence encoding a signal peptide as a first fusion protein wherein the signal peptide directs the cellulase to a first organelle of the transgenic plant wherein the fusion protein protects the transgenic plant from degradation while it is growing; and
(b) at least one DNA encoding a fungal ligninase which is operably linked to a nucleotide sequence encoding a signal peptide as a second fusion protein wherein the signal peptide directs the ligninase to a second different organelle of the transgenic plant, wherein the fusion protein protects the transgenic plant fusion from degradation while growing,wherein the transgenic plant degrades the lignocellulose when ground to produce the plant material.
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Abstract
The present invention provides transgenic plants which after harvest degrade the lignin and cellulose therein to fermentable sugars which can further be fermented to ethanol or other products. In particular, the transgenic plants comprise ligninase and cellulase genes from microbes operably linked to a DNA encoding a signal peptide which targets the fusion polypeptide produced therefrom to an organelle of the plant, in particular the chloroplasts. When the transgenic plants are harvested, the plants are ground to release the ligninase and cellulase which then degrade the lignin and cellulose of the transgenic plants to produce the fermentable sugars.
21 Citations
61 Claims
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1. A transgenic herbaceous plant which degrades lignocellulose when the transgenic plant is ground to produce a plant material comprising:
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(a) at least one DNA encoding a microbial cellulase which is operably linked to a nucleotide sequence encoding a signal peptide as a first fusion protein wherein the signal peptide directs the cellulase to a first organelle of the transgenic plant wherein the fusion protein protects the transgenic plant from degradation while it is growing; and (b) at least one DNA encoding a fungal ligninase which is operably linked to a nucleotide sequence encoding a signal peptide as a second fusion protein wherein the signal peptide directs the ligninase to a second different organelle of the transgenic plant, wherein the fusion protein protects the transgenic plant fusion from degradation while growing, wherein the transgenic plant degrades the lignocellulose when ground to produce the plant material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 54, 57, 58, 59, 60)
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18. A method for producing a transgenic herbaceous plant which degrades lignocellulose when the transgenic plant is ground to produce a plant material comprising:
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(a) providing a first transgenic plant which includes a DNA encoding a microbial cellulase which is operably linked to a nucleotide sequence encoding a signal peptide as a first fusion protein wherein the signal peptide directs the cellulase to a first organelle of the transgenic plant, wherein the fusion protein protects the transgenic plant from degradation while it is growing and a second transgenic plant which includes a DNA encoding a fungal ligninase which is operably linked to a nucleotide sequence encoding a signal peptide as a second fusion protein wherein the signal peptide directs the ligninase to a second different organelle of the transgenic plant, wherein the fusion protein protects the transgenic plant fusion from degradation while growing; and (b) mating by sexual fertilization the first and the second transgenic plants to produce a third transgenic plant which includes the first DNA encoding the cellulase and the second DNA encoding the ligninase, wherein the transgenic plant degrades the lignocellulose when ground to produce the plant material. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method for converting lignocellulose in a plant material to fermentable sugars comprising:
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(a) providing a transgenic herbaceous plant which includes at least one DNA encoding a microbial cellulase which is operably linked to a nucleotide sequence encoding a signal peptide as a first fusion protein wherein the signal peptide directs the cellulase to a first organelle of the transgenic plant, wherein the fusion protein protects the transgenic plant from degradation while it is growing and at least one DNA encoding a fungal ligninase which is operably linked to a nucleotide sequence encoding a signal peptide as a second fusion protein wherein the signal peptide directs the ligninase to a second different organelle of the transgenic plant, wherein the fusion protein protects the transgenic plant fusion from degradation while growing; (b) growing the transgenic plant for a time sufficient for the transgenic plant to accumulate a sufficient amount of the cellulase and the ligninase in the organelle of the transgenic plant; (c) harvesting the transgenic plant which has accumulated the cellulase and ligninase in the organelle of the transgenic plant; (d) grinding the transgenic plant for a time sufficient to produce the plant material wherein the cellulase and ligninase produced by the transgenic plant are released from the organelle of the transgenic plant; (e) incubating the plant material for a time sufficient for the cellulase and ligninase in the plant material to produce the fermentable sugars from the lignocellulose in the plant material; and (f) extracting the fermentable sugars produced from the lignocellulose by the cellulase and the ligninase from the plant material. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56)
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61. The transgenic plant wherein the signal peptide for the ligninase is SEQ ID NO:
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Specification