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

1. A process for producing lipids containing polyunsaturated fatty acids from microorganisms of the order Thraustochytriales by conducting a fermentation of the microorganisms in a 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 in a fed-batch process 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; and

e) recovering at least some of the lipids from the microorganisms;

wherein the lipids are at least 20% by weight of the dry cell weight of the biomass.

2. The process of claim 1 , wherein the microorganisms produce lipids containing polyunsaturated fatty acids when the dissolved oxygen content of the fermentation medium is less than 1% of saturation.

3. The process of claim 1 , wherein the process produces lipids at an average rate of at least 0.5 grams lipids per liter of fermentation medium per hour fermentation.

4. The process of claim 1 , wherein the microorganisms are selected from the group consisting of Thraustochytrium, Schizochytrium , and mixtures thereof.

5. The process of claim 1 , wherein the process produces on average at least 0.2 grams docosahexaenoic acid per liter of fermentation medium per hour fermentation.

6. The process of claim 1 , wherein the microorganisms are Schizochytrium.