NOVELTY - A recombinant photosynthetic microorganism capable of producing a branched-chain alcohol comprising heterologous nucleic acid sequence encoding at least one polypeptide that catalyzes a substrate to product conversion, is new.    USE - The recombinant microorganism is useful for producing branched-chain alcohol chosen from isobutanol, 2-methyl-1-butanol and 3-methyl-1-butanol (claimed) used as fuels or fuel additive.    DETAILED DESCRIPTION - A recombinant photosynthetic microorganism capable of producing a branched-chain alcohol comprising heterologous nucleic acid sequence encoding at least one polypeptide that catalyzes a substrate to product conversion, is new. The polypeptide catalyzes (a) pyruvate to 2-hydroxy-2-methyl-3-oxobutanoate, 2-hydroxy-2-methyl-3-oxobutanoate to 2,3-dihydroxy-3-methylbutanoate, 2,3-dihydroxy-3-methylbutanoate to 3-methyl-2-oxobutanoate, and 3-methyl-2-oxobutanoate to isobutanol (2-methyl-1-propanol), (b) pyruvate to 2-methylmalate, 2-methylmalate to 2-methylmaleate, 2-methylmaleate to D-erythro-3-methylmalate, D-erythro-3-methylmalate to 2-oxobutanoate, threonine to 2-oxobutanoate, pyruvate and 2-oxobutanoate to 2-hydroxy-2-ethyl-3-oxobutanoate, 2-hydroxy-2-ethyl-3-oxobutanoate to 2,3-dihydroxy-3-methylpentanoate, 2,3-dihydroxy-3-methylpentanoate to 3-methyl-2-oxopentanoate, and 3-methyl-2-oxopentanoate to 2-methyl-1-butanol, or (c) pyruvate to 2-hydroxy-2-methyl-3-oxobutanoate, 2-hydroxy-2-methyl-3-oxobutanoate to 2,3-dihydroxy-3-methylbutanoate, 2,3-dihydroxy-3-methylbutanoate to 3-methyl-2-oxobutanoate, 3-methyl-2-oxobutanoate to 2-isopropylmalate, 2-isopropylmalate to 2-isopropylmaleate, 2-isopropylmaleate to 3-isopropylmalate, 3-isopropylmalate to 4-methyl-2-oxopentanoate (2-ketoisocaproate), 4-methyl-2-oxopentanoate to 3-methyl-1-butanol. INDEPENDENT CLAIMS are included for the following:    (1) method for producing a branched-chain alcohol, involves providing culture medium having a carbon source, culturing the above-cited recombinant photosynthetic microorganism in the culture medium under photoautotrophic conditions, and recovering branched-chain alcohol from the culture medium; and    (2) branched-chain alcohol produced by the above-cited method.