The present invention provides isolated or genetically modified strains of microorganisms that display enhanced resistance to acetate as a result of increased expression of a sodium proton antiporter. The present invention also provides methods for producing such microbial strains, as well as related promoter sequences and expression vectors. Further, the present invention provides methods of producing alcohol from biomass materials by using microorganisms with enhanced resistance to acetate.
 This invention was made with government support under Contract Number DE-AC05-00OR22725 between the United States Department of Energy and UT-Battelle, LLC. The U.S. Government has certain rights in this invention.