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

A process for producing microbial lipids comprising:

• a) growing microorganisms of the order Thraustochytriales in a fermentation medium comprising a carbon source and a nitrogen source to increase the biomass density of the fermentation medium to at least 100 g/L on a dry cell weight basis, wherein:
• i) the fermentation medium temperature is at least 20° C.;
• ii) the fermentation medium pH is from about pH 5 to about pH 11;
• iii) the carbon and nitrogen sources are added at rates sufficient to increase the biomass density of the fermentation medium to at least 100 g/L;
• and,
• iv) wherein at least a portion of the carbon source is added during the growing of microorganisms to a biomass density of at least 100 g/L;
• b) limiting a nutrient source other than carbon in the fermentation medium to induce lipid production by the microorganisms after reaching a biomass density of 100 g/L, while maintaining a biomass density of at least 100 g/L on a dry cell weight basis;
• wherein the primary use of the carbon source by the microorganisms is to produce lipids after induction of lipid production and when the biomass density of the fermentation medium is at least 100 g/L on a dry cell weight basis;
• and
• c) recovering the lipids, wherein greater than about 15% of the lipids are polyunsaturated lipids.