This invention relates to the use of microorganisms for the generation of ethanol from lignocellulosic waste materials. Yeast strains of the genus Kluyveromyces which have the capability to ferment cellulose, hexose sugars to ethanol are provided. Also provided are methods for converting cellulose, hexoses, or mixed hydrolysates of hexoses to ethanol by fermentation with Kluyveromyces strains. The invention also provides methods to isolate yeast strains which metabolize cellulose, pentoses, or hemicelluloses from waste materials.
1. A method of producing ethanol from an aqueous medium comprising a saccharide selected from the group consisting of cellobiose, glucose, mannose, galactose, and combinations thereof, the method comprising the steps of
(a) contacting an aqueous medium comprising a saccharide selected from the group consisting of cellobiose, glucose, mannose, galactose, and combinations thereof, with Kluyveromyces marxianus strain SSSJ-0 having ATCC Accession No. PTA-3567 deposited on Jul. 26, 2001; and
(b) incubating the aqueous medium under conditions wherein the saccharide is fermented to ethanol.
2. The method of claim 1 , further comprising the step of recovering the ethanol.
3. The method of claim 1 , wherein the aqueous medium is incubated at a temperature between about 43° C. and about 45° C.
4. A method of producing ethanol from an aqueous medium containing cellulose, the method comprising the steps of
(a) contacting an aqueous medium containing cellulose with Kluyveromyces marxianus strain SSSJ-0 having ATCC Accession No. PTA-3567 deposited on Jul. 26, 2001; and
(b) incubating the aqueous medium under conditions wherein the cellulose is fermented to ethanol.
5. The method of claim 4 , further comprising the step of recovering the ethanol.
6. The method of claim 4 , wherein the aqueous medium is incubated at a temperature between about 43° C. and about 45° C.
7. The method of claim 1 , wherein the saccharide is produced by hydrolyzing polymers of a saccharide source material prior to step (a).
8. The method of claim 7 , wherein the saccharide source material comprises cellulose, hemicellulose, or both.
9. The method of claim 8 , wherein the saccharide source material comprises one or more of hardwoods, softwoods, pulps from papermaking processes, sludges from papermaking processes, fibrous raw materials, and spent grains and liquors from brewing or distilling operations.
10. The method of claim 7 , wherein the hydrolyzing comprises acid hydrolysis.
11. The method of claim 7 , wherein the hydrolyzing comprises enzymatic hydrolysis.
12. The method of claim 1 , wherein the saccharide is fermented in a batch or batch-fed culture system.
13. The method of claim 4 wherein the cellulose source material comprises one or more of hardwoods, softwoods, pulps from papermaking processes, sludges from papermaking processes, fibrous raw materials, and spent grains and liquors from brewing or distilling operations.
14. The method of claim 4 , wherein the cellulose is fermented in a batch or batch-fed culture system.