Pentose fermentation of normally toxic lignocellulose prehydrolysate with strain of Pichia stipitis yeast using air
First Claim
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1. A biologically pure culture of Pichia stipitis strain NPw9 having ATCC accession No. PTA-3717 useful for production of ethanol using oxygen for growth while fermenting toxic lignocellulosic prehydrolysates in excess of 17% equivalent total solids and/or municipal solid waste (MSW) without detoxifying said lignocellulosic prehydrolysates.
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Abstract
Strains of the yeast Pichia stipitis NPw9 (ATCC PTA-3717) useful for the production of ethanol using oxygen for growth while fermenting normally toxic lignocellulosic prehydrolysates.
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Citations
20 Claims
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1. A biologically pure culture of Pichia stipitis strain NPw9 having ATCC accession No. PTA-3717 useful for production of ethanol using oxygen for growth while fermenting toxic lignocellulosic prehydrolysates in excess of 17% equivalent total solids and/or municipal solid waste (MSW) without detoxifying said lignocellulosic prehydrolysates.
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2. A process for the preparation of Pichia stipitis strain NPw9 having ATCC accession No. PTA-3717 comprising:
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a) growing a culture of Pichia stipitis yeast on toxic prehydrolysates of agricultural residues, grain processing intermediates and residues, softwoods, hardwoods or mixtures thereof;
b) maximizing the number of cell generations and using all generated cells by splitting and transferring culture progeny into additional cultures while said yeast have active mitochondria by gradually increasing prehydrolysate concentration while increasing aeration and reducing nutrient concentration in an amount sufficient to obligate yeast dependency on oxygen at an oxygen absorption rate of 0.001 to ≦
0.7 mM of 02 per liter of culture per minute;
c) gradually substituting for yeast extract a lesser amount of corn-steep liquor;
d) replacing a nitrogen source of peptone with a lesser amount of ammonium sulfate, or an inexpensive nitrogen source; and
e) collecting cells of Pichia stipitis strain NPw9 having accession No. PTA-3717. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 20)
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10. A process for preparation of Pichia stipitis strain NPw9 having ATCC accession No. PTA-3717 comprising:
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a) growing a culture of Pichia stipitis;
derived from Northern Regional Research Lab (NRRL), Agricultural Research Service, USDA, on toxic prehydrolysate of a blend of whole tree softwoods, hardwoods, agricultural residues, grain processing intermediates and residues, or mixtures or blends thereof;
b) maximizing the number of cell generations and using all generated cells by splitting and transferring culture progeny into additional cultures while said yeast have active mitochondria by gradually increasing prehydrolysate concentration while increasing aeration and reducing nutrient concentration in an amount sufficient to obligate yeast dependency on oxygen at an oxygen absorption rate of 0.001 to ≦
0.7 mM of 02 per liter of culture per minute;
c) gradually substituting for yeast extract a lesser amount of corn-steep liquor;
d) replacing a nitrogen source of peptone with a lesser amount of ammonium sulfate; and
e) collecting cells of Pichia stipitis strain NPw9 having ATCC accession No. PTA3717. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification