TECHNOLOGY FOCUS - BIOLOGY - Preparation (Claimed): Preparation of the recombinant microorganism, comprises transforming a microorganism optimized for NADH coupling with a polynucleotide encoding enzymes consisting of keto-thiolase, acetyl-CoA acetyltransferase, hydroxybutyryl-CoA dehydrogenase, crotonase, crotonyl-CoA reductase, butyryl-CoA dehydrogenase and/or an alcohol dehydrogenase. Preferred Method: The NADH utilization of the microorganism is optimized by selection of a parental microorganism or through mutagenesis and screening. The NADH utilization is controlled by knocking out competing pathways for NADH utilization or increase production of NADH. Preferred Components: The recombinant microorganism further comprises: reduced ethanol dehydrogenase activity, lactate dehydrogenase activity, furmarate reductase activity, phosphate acetyltransferase activity, and/or formate acetyltransferase activity; and reduced expression of an oxygen dependent transcription regulator. The microorganism comprises a heterologous trans-2-enoyl-CoA reductase (ter). The ter is derived from a Treponema denticola, or F. succinogenes and comprises an M11K substitution. The recombinant microorganism comprises elevated expression of a polypeptide having keto thiolase activity, as compared to a parental microorganism, where the recombinant microorganism produces a metabolite comprising acetoacetyl-CoA from a substrate comprising acetyl-CoA. The polypeptide having keto thiolase activity is encoded by a polynucleotide having at least 50% identity to a sequence of SEQ ID No. 1 (comprising a fully defined 1164 base pair sequence given in the specification), SEQ ID No. 3 (comprising a fully defined 2190 base pair sequence given in the specification) and SEQ ID No. 5 (comprising a fully defined 1185 base pair sequence given in the specification), or SEQ ID No. 1 and SEQ ID No. 3. The polypeptide having keto thiolase activity is encoded by an atoB gene, fadA gene or their homologs derived from the genus Escherichia. The Escherichia is E. coli. The recombinant microorganism comprises: elevated expression of a polypeptide having acetyl-CoA acetyltransferase, as compared to a parental microorganism, where the recombinant microorganism produces a metabolite comprising acetoacetyl-CoA from a substrate comprising acetyl-CoA; elevated expression of a polypeptide having hydroxybutyryl-CoA dehydrogenase activity, as compared to a parental microorganism, where the recombinant microorganism produces a metabolite comprising 3-hydroxybutyryl-CoA from a substrate comprising acetoacetyl-CoA; elevated expression of a polypetpide having crotonase activity, as compared to a parental microorganism, where the recombinant microorganism produces a metabolite comprising crotonyl-CoA from a substrate comprising 3-hydroxybutyryl-CoA; elevated expression of a polypeptide having crotonyl-CoA reductase, as compared to a parental microorganism, where the recombinant microorganism produces a metabolite comprising butyryl-CoA from a substrate comprising crotonyl-CoA; elevated expression of a polypeptide having butyryl-CoA dehydrogenase, as compared to a parental microorganism, where the recombinant microorganism produces a metabolite comprising butyryl-CoA from a substrate comprising crotonyl-CoA; and elevated expression of a polypeptide having aldehyde/alcohol dehydrogenase activity, as compared to a parental microorganism, where the recombinant microorganism produces a metabolite comprising buteraldehyde from a substrate comprising butyryl-CoA. The polypeptide having acetyl-coA acetyltransferase activity is encoded by: a polynucleotide having at least about 50% identity to a sequence of SEQ ID No. 7 (comprising a fully defined 1179 base pair sequence given in the specification); a thl gene or its homolog; and a polynucleotide having at least 50% identity to a sequence of SEQ ID No. 11 (comprising a fully defined 849 base pair sequence given in the specification). The thl gene is derived from the genus Clostridium. The Clostridium is C. acetobutylicum. The hydroxybutyryl-CoA dehydrogenase is encoded by an hbd gene or its homolog. The hbd gene is derived from a microorganism consisting of Clostridium acetobutylicum (preferred), Clostridium difficile, Dasytricha ruminantium, Butyrivibrio fibrisolvens, Treponema phagedenis, Acidaminococcus fermentans, Clostridium kluyveri, Syntrophospora bryanti, and Thermoanaerobacterium thermosaccharolyticum. The polypeptide having crotonase activity is encoded by a polynucleotide having at least 50% identity to a sequence of SEQ ID No. 9 (comprising a fully defined 786 base pair sequence given in the specification). The crotonase is encoded by a crt gene or its homolog. The crt gene is derived from a microorganism consisting of Clostridium acetobutylicum (preferred), Butyrivibrio fibrisolvens, Thermoanaerobacterium thermosaccharolyticum, and Clostridium difficile. The polypeptide having crotonyl-coA reductase activity is encoded by a polynucleotide having at least 50% identity to a sequence of SEQ ID NOs. 50, 52, 54, 56, 58, 60 and 62. The polypeptide having crotonyl-CoA reductase is encoded by a ccr gene or its homolog. The ccr gene is derived from the genus Streptomyces. The Streptomyces is S. coelicolor or S. collinus. The polypeptide having butyryl-CoA dehydrogenase activity is encoded by a polynucleotide having at least 50% identity to a sequence of SEQ ID No. 13 (comprising a fully defined 1140 base pair sequence given in the specification) or SEQ ID No. 19 (comprising a fully defined 1152 base pair sequence given in the specification). The polypeptide having butyryl-CoA dehydrogenase activity is encoded by a bed gene or its homolog. The bed gene is derived from Clostridium acetobutylicum, Mycobacterium tuberculosis, or Megasphaera elsdenii. The polypeptide having aldehyde/alcohol dehydrogenase activity is encoded by a polynucleotide having at least 50% identity to a sequence of SEQ ID No. 39 (comprising a fully defined 2577 base pair sequence given in the specification). The polypeptide having aldehyde/alcohol dehydrogenase is encoded by an aad gene, an adhE2 gene or their homolog. The aad gene or adhE2 gene is derived from Clostridium acetobutylicum. The suitable carbon substrate comprises glucose. The recombinant microorganism comprises one or more deletions or knockouts in a gene encoding an enzyme that catalyzes the conversion of acetyl-coA to ethanol, catalyzes the conversion of pyruvate to lactate, catalyzes the conversion of fumarate to succinate, catalyzes the conversion of acetyl-coA and phosphate to coA and acetyl phosphate, catalyzes the conversion of acetyl-coA and formate to coA and pyruvate, or condensation of the acetyl group of acetyl-CoA with 3-methyl-2-oxobutanoate (2-oxoisovalerate). The recombinant microorganism comprises the deletion or disruption of adhE, idhR, frdBC, ptar, pta, fnr and/or their homologs or variants. The microorganism comprises a reduction or inhibition in the conversion of acetyl-coA to ethanol. The recombinant microorganism comprises a reduction of an ethanol dehydrogenase thereby providing a reduced ethanol production capability. The microorganism is derived from E. coli. The ethanol dehydrogenase is an adhE or its homolog or variant. The recombinant microorganism comprises a deletion or knockout consisting of Delta adhE, Delta ldhA, Delta pta, Delta frdB, Delta frdC, Delta frdBC, Delta fnr, Delta pta and/or Delta pfIB. The recombinant microorganism comprises an expression or increased expression of an atoB, thl, adhE2, hbd, crt, bed, and/or ccr. The microorganism is engineered to reduce or knockout expression of a gene encoding an enzyme that catalyzes the conversion of acetyl-coA to ethanol, pyruvate to lactate, fumarate to succinate, acetyl-coA, phosphate to coA and acetyl phosphate and acetyl-coA and formate to coA and pyruvate, or condensation of the acetyl group of acetyl-CoA with 3-methyl-2-oxobutanoate (2-oxoisovalerate), where the sequences not defined here may be found at ftp://ftp.wipo.int/pub/published-pct-sequences/publication. EXAMPLE - No suitable example given.