Abstract: The present invention provides recombinant microorganisms comprising isobutanol producing metabolic pathway with at least one isobutanol pathway enzyme localized in the cytosol, wherein said recombinant microorganism is selected to produce isobutanol from a carbon source. Methods of using said recombinant microorganisms to produce isobutanol are also provided. In various aspects of the invention, the recombinant microorganisms may comprise a cytosolically active isobutanol pathway enzymes. In some embodiments, the invention provides mutated, modified, and/or chimeric isobutanol pathway enzymes with cytosolic activity. In various embodiments described herein, the recombinant microorganisms may be microorganisms of the Saccharomyces clade, Crabtree-negative yeast microorganisms, Crabtree-positive yeast microorganisms, post-WGD (whole genome duplication) yeast microorganisms, pre-WGD (whole genome duplication) yeast microorganisms, and non-fermenting yeast microorganisms.

Abstract: The present invention is generally provides recombinant microorganisms comprising engineered metabolic pathways capable of producing C3-C5 alcohols under aerobic and anaerobic conditions. The invention further provides ketol-acid reductoisomerase enzymes which have been mutated or modified to increase their NADH-dependent activity or to switch the cofactor preference from NADPH to NADH and are expressed in the modified microorganisms. In addition, the invention provides isobutyraldehyde dehydrogenase enzymes expressed in modified microorganisms. Also provided are methods of producing beneficial metabolites under aerobic and anaerobic conditions by contacting a suitable substrate with the modified microorganisms of the present invention.