NOVELTY - Producing a commodity chemical or its intermediate comprises growing a recombinant microorganism with a source of an aldehyde and/or a ketone. The recombinant microorganism comprises at least one polynucleotide encoding and expressing a polypeptide having an: aldolase activity; and alcohol dehydrogenase activity, where the polynucleotide is exogenous.    USE - The method is useful for producing commodity chemicals, useful as biofuels e.g. isooctane, 2-ethylhexane and 2-butyloctane, which are useful for blending the refinery-petroleum product including gasoline, jet fuel and diesel for producing commodity chemical enriched refinery-produced petroleum products (all claimed).    ADVANTAGE - The method provides commodity chemicals: with reduced green house gas emissions by more than 80%, thus it is environmentally friendly; which can be utilized directly by existing engines; that require simple technical process; and which are compatible with existing infrastructure in the oil and gas industry.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) the recombinant microorganism;    (2) producing the commodity chemical or its intermediate, comprising growing the first recombinant microorganism with a source of a monosaccharide or oligosaccharide, where the first recombinant microorganism comprises (i) an aldehyde or ketone biosynthesis pathway, (ii) at least one polynucleotide encoding and expressing a polypeptide having an aldolase activity, and (iii) at least one polynucleotide encoding and expressing a polypeptide having an alcohol dehydrogenase activity;    (3) producing the commodity chemical or its intermediate, comprising growing the recombinant microorganism with a biomass-derived polysaccharide, where the recombinant microorganism is capable of growing on the biomass-derived polysaccharide as a sole source of carbon;    (4) the commodity chemical produced by the above method; and    (5) a blended commodity chemical comprising the above commodity chemical and a refinery-produced petroleum product.