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. The scaffoldin gene cipA from Clostridium thermocellum is modified to generate a mutated gene with enhanced genetic stability. This mutated cipA gene can be introduced into a heterologous host, such as Thermoanaerobacterium saccharolyticum. Other cellulosome components may be introduced into the host to build a full-sized cellulosome in T. saccharolyticum. Manipulation of the scaffoldin genes provides a new approach for enhancing ethanol production by biomass-fermenting microorganisms.

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.