TECHNOLOGY FOCUS - BIOLOGY - Preferred Cell: When the cell expresses genes selected from (a), (b) and (c), then the cell recombinantly expresses: a gene encoding an acetoacetyl-CoA thiolase that condenses one acetyl-CoA with one propionyl-CoA to form 3-ketovaleryl-CoA; genes encoding a 3-hydroxybutyryl-CoA reductase, an enoyl-CoA hydratase, and a butyryl-CoA dehydrogenase; and a gene encoding a bi-functional aldehyde/alcohol dehydrogenase. Both the cells recombinantly expresses a bktB gene; a hbd gene and a crt gene, or a phaB gene and a phaJ1 gene; a bcd-etfAB gene pair; and an adhE gene. The cell does not express an mdh gene. The adhE gene is codon-optimized. The cell recombinantly expresses a thr-fr gene, a thrB gene, a thrC gene, and a ilvA-fr gene. The cell endogenously or recombinantly expresses a gene encoding pyruvate dehydrogenase complex (PDHc) or a gene encoding pyruvate-formate lyase (PfIB). The cell endogenously or recombinantly expresses a gene encoding anaerobically active PDHc. The cell recombinantly expresses a ptb-buk gene pair or a pet gene. Preferred Components: The recombinantly expressed gene is expressed from the plasmids. The recombinantly expressed gene is integrated into the genome of the cell. The hbd gene, crt gene, bcd-etfAB gene pair, and/or adhE gene is a Clostridium acetobutylicum gene. The bktB gene and/or phaB gene is a Ralstonia eutropha gene. The bktB gene and/or phaB gene is a Ralstonia eutropha H16 gene. The phaJ1 gene is a Pseudomonas aeruginosa gene. Preferred Method: The method (M1) further involves feeding valerate, glucose, propionate or glycerol to the cell; and recovering pentanol from the cell or from the culture medium in which the cell is grown. The headspace to culture volume ratio is less than or equal to 4. When the cell expresses genes selected from (a), (b) and (c), then the method (M2) further involves: recombinantly expressing in the cell the gene encoding the acetoacetyl-CoA thiolase, the genes encoding 3-hydroxybutyryl-CoA reductase, enoyl-CoA hydratase, and butyryl-CoA dehydrogenase, and the gene encoding bi-functional aldehyde/alcohol dehydrogenase. The method (M2) further involves recombinantly expressing in the cell: bktB gene; hbd gene and a crt gene, or a phaB gene and a phaJ1 gene; bcd-etfAB gene pair; and adhE gene; recombinantly expressing in the cell thr-fr gene, a thrB gene, a thrC gene, and a ilvA-fr gene; culturing the cell in cell culture medium; feeding valerate, glucose, propionate or glycerol to the cell; and recovering pentanol from the cell or from the culture medium in which the cell is grown. EXAMPLE - No suitable example given.