Oxygen influence on the ß-oxidative metabolism of methyl ricinoleate for lactones production by the yeast Yarrowia lipolytica

The yeast Yarrowia lipolytica is able to carry out the peroxisomal b-oxidative catabolism of methyl ricinoleate, a process leading notably to the production of g-decalactone, a high-value aroma compound. In fact, this metabolic pathway gives rise to different C10 lactones and their accumulations report the efficiency of the peroxisomal beta-oxidation enzymes. gamma-Decalactone or 3-hydroxydecan-4-olide accumulate when acyl-CoA oxidase or 3-hydroxyacyl-CoA dehydrogenase, respectively, control the flux within the pathway. We investigated the accumulation of C10 lactones in various aeration conditions. An important accumulation of 3-hydroxydecan-4-olide was observed when increasing the aeration up to a certain point, above it its concentration was lowered, which indicates a stimulation of the activity of 3-hydroxyacyl-CoA
dehydrogenase. Cultures under high-pressure were performed in order to increase the oxygen in the medium by an alternative mean. Y. lipolytica growth in glucose medium was accelerated at 0.5 MPa of total air pressure. A decrease in g-decalactone production was observed with the increase in pressure. Curiously, applying a pressure of 0.5 MPa during growth and then during biotransformation resulted in high decenolides concentrations.