Enhanced production of lipids containing polyenoic fatty acid by very high density cultures of eukaryotic microbes in fermentors

A process for producing lipids containing polyunsaturated fatty acids from microorganisms of the order Thraustochytriales by conducting a fermentation of the microorganisms in a fermentation medium comprising a carbon source, the process comprising:

• a) providing the fermentation medium comprising the carbon source;
• b) adding the microorganisms to the fermentation medium;
• c) adding an additional amount of the carbon source to the fermentation medium to increase the biomass density of the fermentation medium when the dissolved oxygen content of the fermentation medium is at least 4% of saturation;
• d) allowing the dissolved oxygen content of the fermentation medium to decrease to less than about 3% of saturation;
• wherein lipid production is induced in the microorganisms;
• and
• e) recovering at least some of the lipids from the microorganims;
• wherein at least 15% of the lipids are produced by the microorganisms as polyunsaturated fatty acids.