Role of beta-oxidation enzymes in gamma-decalactone production by the yeast Yarrowia lipolytica

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