Abstract: The present invention is directed to the construction of prototrophic, cellulo lytic strains of Saccharomyces cerevisiae with tethered and secreted cellulases and selection-based improvement of growth on cellulose by these strains. In some embodiments, host cells of the invention are able to produce ethanol using crystalline cellulose as a sole carbon source.

Abstract: A process for the pretreatment of lignocellulosic biomass is provided. The process generally includes flowing water through a pretreatment reactor containing a bed of particulate ligno-cellulosic biomass to produce a pressurized, high-temperature hydrolyzate exit stream, separating solubilized compounds from the hydrolyzate exit stream using an inorganic nanoporous membrane element, fractionating the retentate enriched in solubilized organic components and recycling the permeate to the pretreatment reactor. The pretreatment process provides solubilized organics in concentrated form for the subsequent conversion into biofuels and other chemicals.

Abstract: A process for the pretreatment of lignocellulosic biomass is provided. The process generally includes flowing water through a pretreatment reactor containing a bed of particulate ligno-cellulosic biomass to produce a pressurized, high-temperature hydrolyzate exit stream, separating solubilized compounds from the hydrolyzate exit stream using an inorganic nanoporous membrane element, fractionating the retentate enriched in solubilized organic components and recycling the permeate to the pretreatment reactor. The pretreatment process provides solubilized organics in concentrated form for the subsequent conversion into biofuels and other chemicals.

Abstract: The present invention provides isolated nucleic acid molecules which encode a mutant acetaldehyde-CoA/alcohol dehydrogenase or mutant alcohol dehydrogenase and confer enhanced tolerance to ethanol. The invention also provides related expression vectors, genetically engineered microorganisms having enhanced tolerance to ethanol, as well as methods of making and using such genetically modified microorganisms for production of biofuels based on fermentation of biomass materials.

Abstract: The present invention provides isolated nucleic acid molecules which encode a mutant acetaldehyde-CoA/alcohol dehydrogenase or mutant alcohol dehydrogenase and confer enhanced tolerance to ethanol. The invention also provides related expression vectors, genetically engineered microorganisms having enhanced tolerance to ethanol, as well as methods of making and using such genetically modified microorganisms for production of biofuels based on fermentation of biomass materials.

Abstract: Bacteria consume a variety of biomass-derived substrates and produce ethanol. Hydrogenase genes have been inactivated m Thermoanaerobacterium saccharolyticum to generate mutant strains with reduced hydrogenase activities. One such mutant strain with both the ldh and hydtrA genes inactivated shows a significant increase in ethanol production. Manipulation of hydrogenase activities provides a new approach for enhancing substrate utilization and ethanol production by biomass-fermenting microorganisms.

Abstract: The present invention is directed to the construction of prototrophic, cellulo lytic strains of Saccharomyces cerevisiae with tethered and secreted cellulases and selection-based improvement of growth on cellulose by these strains. In some embodiments, host cells of the invention are able to produce ethanol using crystalline cellulose as a sole carbon source.

Abstract: A semi-continuous simultaneous saccharification and fermentation (SSF) process for the bioconversion of cellulose into ethanol and other organic chemicals is disclosed. The process provides for substantially higher substrate conversion at a given enzyme loading (or alternatively a lower enzyme loading used to achieve the same conversion) in a reactor operated according to a semi-continuous feeding protocol.