Xylose-fermenting recombinant yeast strains
Disclosed are xylose-fermenting recombinant yeast strains comprising heterologous PsXYL1, Ps XYL2, and PsXYL3, as well as methods of fermenting xylose to obtain ethanol using the recombinant yeast strain.
1. A recombinant xylose-fermenting respiration deficient Saccharomyces cerevisiae yeast strain comprising heterologous polynucleotide sequences encoding xylose reductase, xylitol dehydrogenase, and D-xylulokinase.
2. The recombinant strain of claim 1 , wherein the strain has reduced respiration relative to that of the strain from which it was derived.
3. The recombinant strain of claim 1 , wherein the strain is deposited as NRRL Y-30603.
4. A method of producing ethanol from the fermentation of xylose comprising: culturing the recombinant strain of claim 1 with xylose-containing material under suitable conditions for a period of time sufficient to allow fermentation of xylose to ethanol.
5. The method of claim 4 , wherein the recombinant strain is caused to have reduced respiration relative to the strain from which it was derived.
6. The method of claim 4 , wherein the recombinant strain ferments xylose to ethanol at a higher rate than the strain from which it was derived.
7. The method of claim 5 , wherein the recombinant strain is the strain deposited as NRRL Y-30603.
8. The recombinant strain of claim 1 , wherein the yeast is a petite mutant.
9. The method of claim 4 , wherein the recombinant strain is deposited as NRRL Y-30602.
10. The method of claim 4 , wherein the recombinant strain is a respiration deficient mutant of the strain deposited as NRRL Y-30602.
11. A recombinant Saccharomyces cerevisiae strain deposited as NRRL Y-30602.
12. A respiration deficient mutant of the recombinant Saccharomyces cerevisiae strain of claim 11 .