Biosynthesis of lipids and organic acids by Yarrowia lipolytica strains cultivated on glucose

The biochemical behavior of wild-type or genetically modified (presenting decreased expression of intracellular acyl-CoA oxidases) Yarrowia lipolytica strains cultivated on commercial glucose was studied. Flask nitrogen-limited cultures were performed favoring the production of organic acids (and potentially the accumulation of lipid). Nitrogen depletion induced secretion of citric acid, while intracellular lipid was not produced in high quantities. Maximum total citric acid up to 49 g/L (yield 0.85 g/g glucose) was produced. In some of the wild-type strains, an increase of glucose in the medium also induced noticeable production of acetic acid. Increasing the amount of added glucose led to an increase in the total lipid quantity (%) produced, although in the stationary growth phase the concentration of lipid declined, indicating lipid degradation even for the genetically modified strains. Total lipid amount did not exceed the value of 14%, while neutral fractions increased with increase in glucose concentration. In all cases, the total microbial lipids and major lipid fractions were composed of C-16 and C-18 (principally unsaturated) fatty acids. Finally, in several of the strains cultured in media containing a low glucose concentration, unicellular morphology was observed, while at high glucose concentrations mycelia were predominant.