Abstract: A method of producing bi-functional fatty acids comprising introducing into a host cell or organism, which comprises one or more ?- or ?-1 functionalized acyl-CoAs, and expressing therein a KASIII, which can use one or more of the ?- or ?-1 functionalized acyl-CoAs as a substrate; a method of producing a ?-1 hydroxy branched fatty acid, a ?-1 branched fatty acid, or a combination thereof by culturing a mutant E. coli, which does not express a functional KASIII from the endogenous fabH gene and expresses a phaA and a phaB and a functional exogenous KASIII; and a mutant E. coli, a method of making the mutant, a culture comprising the mutant, and a composition comprising ?-1 hydroxy branched fatty acids, a ?-1 branched fatty acids, or a combination thereof obtained from the culture.