TECHNOLOGY FOCUS - BIOLOGY - Preparation: No preparation method is given. Preferred Components: The icmA and icmB (genes) of Escherichia coli encodes the isobutyryl-coenzyme A mutase. The recombinant microorganism additionally comprises a genetic modification to increase metabolic production of isobutyryl-coenzyme A. The genetic modification comprises addition of at least one heterologous nucleic acid sequence: that encodes at least one of acetolactate synthase, acetohydrozybutanoate synthase, acetohydroxy acid isomeroreductase, dihyxroxy acid dehyratase or branched chain dehyrdogenase; that encodes at least one of ilvN/b, ilvC, ilvD or bkdA1,A2,B (branched chain dehydrogenase of Pseudomonas putida). The recombinant microorganism converts isobutyryl-coenzyme A to isobutanol. The recombinant microorganism comprises: the enzymatic activities of variations 1 and 2 of figure-1 (as given in the specification); at least one of a 3-hydroxyisobutyrate hydrolase of Homosapiens (HHYD), a gamma -aminobutyraldehyde dehydrogenase (ABAL) of Rattus norvegicus (ABAL dehydrogenase), an alcohol dehydrogenase of Saccharomyces cerevisiae (ADH6/ypr1), and an alcohol dehydrogenase of E. coli (yqhD); at least one of an aldehyde dehydrogenase of Giardia lamblia, an alcohol dehydrogenase of S. cerevisiae (ADH6/ypr1) or an alcohol dehydrogenase of E. coli (yqhD). The nucleic acid sequence: encodes bkdA1, bkdA2, bkdB and optionally at least one enzyme comprising ilv N/B, ilvC or ilvD; encodes icmAB, where the recombinant microorganism biosynthesizes butanol from 2-acetolactate; additionally encodes for bio-production of isobutanol from isobutyryl-CoA, where the microorganism expresses enzymes for bio-production of isobutanol from isobutyryl-CoA; additionally encodes for and the microorganism expresses HHYD, an aldehyde dehydrogenase and an alcohol dehydrogenase; additionally encodes for and the microorganism expresses an aldehyde dehydrogenase, and an alcohol dehydrogenase but not HHYD; additionally encodes for bio-production of isobutanol and/or butanol from isobutyryl-Co enzyme A, where the microorganism expresses a butyraldehyde dehydrogenase and a butanol dehydrogenase and does not express enzymes converting isobutyryl-Co enzyme A to isobutanol; encodes an enzyme comprising one or both of butyraldehyde dehydrogenase and butanol dehydrogenase activities; encodes enzymes providing functionality of variation 1 and/or variation 2 of Pathway B as given in the specification; encodes icmAB and isobutanol is a product of the recombinant microorganism biosynthesized from acetoacetyl-Coenzyme A; or additionally encodes for and the microorganism expresses enzymes for bio-production of butanol from isobutyryl-Co enzyme-A. The aldehyde dehydrogenase is a gamma -aminobutyraldehyde dehydrogenase of R. norveaicus. The recombinant microorganism comprises a genetic modification of at least one enzyme to decrease or eliminate bio-production of a metabolic product other than butanol and/or isobutanol. The recombinant microorganism comprises a genetic modification of at least one other enzyme to decrease or eliminate bio-production of a metabolic product other than butanol and/or isobutanol, where the other metabolic product is lactic acid. The genetic modification of one other enzyme is D-lactate dehydrogenase (Idha), which is effective to decrease conversion of pyruvate to acetyl-coenzyme A, where the modification results in decreased activity of an enzyme having lactose dehydrogenase function and decreased activity of an enzyme having pyruvate/formate lyase function. The recombinant microorganism is modified from mutant JW1375 or mutant NZN111. The polypeptide encoded by a nucleic acid sequence has at least 90%, preferably 95% homology with the polypeptide encoded by any nucleic acid sequence as given in the specification. The media is a minimal media. EXAMPLE - No suitable example given.