NOVELTY - An isolated nucleic acid encoding a polypeptide of no more than 1500 amino acid residues comprising an amino acid sequence selected from SEQ ID NOs: 64-74 and 91-133, is new.    USE - The nucleic acid and polypeptide are useful for producing hydrocarbon, aliphatic ketone, and biofuels (claimed).    ADVANTAGE - The present invention provides an improved method of producing biofuels. The invention provides nucleic acid sequences that encode polypeptides that are involved in the biosynthesis of hydrocarbons and hydrocarbon intermediates. The invention provides methods of using the same for the production of biofuels.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a vector comprising the isolated nucleic acid above;    (2) a cell comprising the isolated nucleic acid or the vector above, transformed with an isolated nucleic acid or transfected with the vector;    (3) a method for producing a hydrocarbon by culturing the cell with a substrate under conditions to produce a hydrocarbon, or incubating a substrate with OleA, OleB, OleC, OleBC, OleD, or their combination under conditions for producing a hydrocarbon;    (4) a method for producing aliphatic ketone by culturing the cell with a substrate under conditions to produce aliphatic ketone or incubating a substrate with OleA under conditions for producing an aliphatic ketone;    (5) a method for producing a purified polypeptide by culturing the cell under conditions to produce the polypeptide encoded by the isolated nucleic acid;    (6) a method for producing biofuels by performing the method above;    (7) a hydrocarbon produced by the method of (4) having a delta 13C of -28 or greater and having a pMC of at least 50;    (8) a biofuel comprising the hydrocarbon;    (9) an isolated polypeptide comprising an amino acid sequence selected from SEQ ID NO: 2, 4, 6, 8, 12, 14, 16, 18, 20, or 22 where the amino acid sequence comprises one or more amino acid substitutions, additions, insertions, or deletions;    (10) a genetically engineered organism comprising an exogenous nucleic acid sequence stably incorporated into the genome of an organism upstream of a genomic nucleic acid sequence that (i) has at least 35% sequence identity to a nucleic acid sequence selected from ODD SEQ ID NOS: 10-21 or SEQ ID NO: 5, 7, or 87 and (ii) encodes a polypeptide; and    (11) a method for identifying an enzyme useful for the production of hydrocarbons by transforming a cell comprising polypeptides selected from OleA and OleD, OleA and OleC, and OleC and OleD with a nucleic acid encoding an enzyme suspected of having the ability to produce hydrocarbons, and determining whether the cell produces hydrocarbons, where the existence of hydrocarbon production by the cell indicates that the nucleic acid encodes a polypeptide useful for the production of hydrocarbons.