NOVELTY - Recombinant microorganism comprising a genetic modification to provide a nucleic acid sequence that encodes an isobutyryl-coA mutase, is new, where the recombinant microorganism is adapted to produce butanol.    USE - The recombinant microorganism is useful in a bio-production system for bio-synthesizing butanol and/or isobutanol (all claimed) from carbon sources other than petroleum, where the butanol and/or isobutanol are useful as biofuels and solvents.    ADVANTAGE - The recombinant microorganism produces: butanol and/or isobutanol in an industrial scale (high yield); and reduces or eliminates the bio-production of undesired metabolic products during the biosynthesis process.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a recombinant microorganism comprising at least one expression cassette comprising a nucleic acid sequence that encodes at least one polypeptide having one or more enzyme activities of a biosynthetic pathway for bio-production of butanol and/or isobutanol, where the biosynthetic pathway comprises acetolactate synthase activity and/or acetohydrozybutanoate synthase activity or acetyl-Coenzyme A acetyltransferase activity, which is adapted to biosynthesize butanol and/or isobutanol;    (2) a recombinant microorganism comprising enzymes to provide the alternative approaches for the bio-production of butanol and/or isobutanol;    (3) a bio-production system comprising a bioreactor vessel, the above recombinant microorganism, a carbon source and a media, where the system is adapted to conduct a bio-production event under suitable conditions and for a suitable time to produce a measurable quantity of butanol and/or isobutanol;    (4) a method of biosynthesis of butanol and/or isobutanol, comprising providing a butanol producing genetically modified microorganism, a carbon source and a media in a bioreactor vessel and conducting a bio-production event under suitable conditions and for a suitable time to obtain a measurable quantity of butanol and/or isobutanol; and    (5) an industrial-scale microbial bioreactor system comprising a bioreactor vessel, a carbon source, the above recombinant microorganism and a media.