Role of β-oxidation enzymes in γ-decalactone production by the yeast Yarrowia lipolytica

Some microorganisms can transform methyl ricinoleate into gamma -decalactone, a valuable aroma compound, but yields of the bioconversion are low due to (i) incomplete conversion of ricinoleate (C-18) to the C-10 precursor of gamma -decalactone, (ii) accumulation of other lactones (3-hydroxy-7-decalactone and 2- and 3-decen-4-olide), and (iii) gamma -decalactone reconsumption. We evaluated acyl coenzyme A (acyl-CoA) oxidase activity (encoded by the POX1 through POX5 genes) in Yarrowia lipolytica in lactone accumulation and gamma -decalactone reconsumption in POX mutants. Mutants with no acyl-CoA oxidase activity could not reconsume gamma -decalactone, and mutants with a disruption of pox3, which encodes the short-chain acyl-CoA oxidase, reconsumed it more slowly. 3-Hydroxy-gamma -decalactone accumulation during transformation of methyl ricinoleate suggests that, in wild-type strains, beta -oxidation is controlled by 3-hydroxyacyl-CoA dehydrogenase. In mutants with low acyl-CoA oxidase activity, however, the acyl-CoA oxidase controls the beta -oxidation flux. We also identified mutant strains that produced 26 times more gamma -decalactone than the wild-type parents.