Effect of Origanum vulgare L. Essential Oil on Growth and Lipid Profile of Yarrowia lipolytica Cultivated on Glycerol-Based Media

Aim of the present study was to identify the chemical composition of Origanum vulgare L. essential oil and to investigate its effect on the biochemical behavior of the yeast Yarrowia lipolytica. Twenty-three compounds were identified by GC-MS analysis, representing the 92.3% (w/w) of the total essential oil of the plant. Carvacrol (56.3%) and thymol (16.4%) were the major components. Additionally, shake-flask cultivations of Y. lipolytica were performed, with various essential oil additions (0.05-2 mL/L of medium) on glycerol-based media. Growth was affected even at low concentrations (0.05 mL/L), while in higher essential oil concentrations, strong inhibition phenomena were observed. A tolerance-threshold concentration for the strain was hence established at 0.15 mL/L of oil. Furthermore, the presence of the essential oil in the culture medium resulted in changes in the composition of the intra-cellular lipids of the yeast. Specifically, oil addition to nitrogen-limited cultures to a level > 0.15 mL/L caused a substantial increase in the percentage of saturated fatty acids (C16:0 and C18:0) in the lipid composition of the yeast Y. lipolytica.