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 biologically pure culture of Kluyveromyces marxianus strain SSSJ-0 having ATCC Accession No. PTA-3567 deposited on Jul. 26, 2001, wherein the culture is capable of proliferation in an aqueous medium comprising a pentose as the sole carbon source.
2. The biologically pure culture of claim 1 , wherein the pentose is selected from the group consisting of xylose and L-arabinose.
3. A biologically pure culture of Kluyveromyces marxianus strain SSSJ-0 having ATCC Accession No. PTA-3567 deposited on Jul. 26, 2001, wherein the culture is capable of growth in an aqueous medium, wherein the sole carbon source is selected from the group consisting of cellulose, carboxymethylcellulose derivative, recycled paper sludge, brewer's spent grain, corn stover hydrolysate, sugared lignin hydrolysate, and combinations thereof.
4. The biologically pure culture of claim 3 , wherein the culture is further capable of fermenting the cellulose or carboxymethylcellulose to ethanol.
5. 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 the biologically pure culture of claim 1 ; and
(b) incubating the aqueous medium under conditions wherein the saccharide is fermented to ethanol.
6. The method of claim 5 , further comprising the step of recovering the ethanol.
7. The method of claim 5 , wherein the aqueous medium is incubated at a temperature between about 43° C. and about 45° C.
8. 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 the biologically pure culture of claim 3 ; and
(b) incubating the aqueous medium under conditions wherein the cellulose is fermented to ethanol.
9. The method of claim 8 , further comprising the step of recovering the ethanol.
10. The method of claim 8 , wherein the aqueous medium is incubated at a temperature between about 43° C. and about 45° C.