TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation: The microorganisms (M1) are produced via introduction of genetic material into a host or parental microorganism and/or by modification of the expression of native genes, thereby modifying or altering the cellular physiology and biochemistry of the microorganism. Preferred Microorganism: The native enzyme is xylose reductase (XR) or xylitol dehydrogenase (XDH). The recombinant microorganism (M1) is further engineered to exhibit reduced activity of a native enzyme that catalyzes the conversion of xylitol to xylulose. The recombinant microorganism further comprises the overexpression of a heterologous or native gene encoding for an enzyme that catalyzes the conversion of xylose to xylulose. The gene encodes xylose isomerase (XI). The recombinant microorganism further comprises the overexpression of a heterologous or native gene encoding for an enzyme that catalyzes the conversion of xylulose to xylulose-5-phosphate. The native gene encodes a xylulose kinase (XK). The microorganism (M1) is engineered to eliminate pyruvate decarboxylase (PDC) activity and glycerol 3-phosphate dehydrogenase (GPD) activity. At least one PDC gene and at least one GPD gene is deleted, preferably all PDC genes and all GPD genes are deleted. The polypeptide is acetolactate synthase (ALS). The ALS is a cytosolically-localized ALS. The cytosolically-localized ALS is encoded by L. lactis (alsS), or B. subtilis (alsS). The isobutanol producing metabolic pathway comprises genes encoding an NADH-dependent ketol-acid reductoisomerase (KARI) and an NADH-dependent alcohol dehydrogenase (ADH). The KARI and/or ADH show at least a 10-fold higher catalytic efficiency using NADH as the cofactor, as compared to the wild-type E.coli (KARI IIvC), and a native E.coli (ADH YqhD), respectively. The KARI and/or the ADH have been modified or mutated to be NADH-dependent. The KARI and/or the ADH has been identified in nature with increased activity using NADH as a cofactor as compared to the wild-type E.coli (KARI HvC), and a native E.coli (ADH YqhD), respectively. The microorganism is engineered to exhibit reduced (PDH) activity. The microorganism has an increased capacity to produce acetolactate. The microorganism is yeast of a genus selected from: Saccharomyces, Kluyveromyces, Candida, Pichia, Issatchenkia, Debaryomyces, Hansenula, Yarrowia, and Schizosaccharomyces. EXAMPLE - No suitable example is given.