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

Abstract

The present invention provides a process for growing eukaryotic microorganisms which are capable of producing lipids, in particular lipids containing polyenoic fatty acids. The present invention also provides a process for producing eukaryotic microbial lipids.

1 .- 22 . (canceled) 
     
     
         23 . A biomass of microorganisms having highly unsaturated fatty acids, wherein said biomass is produced by a process of conducting a fermentation of the microorganisms in a fermentation medium comprising a carbon source and a limiting nutrient source, the process comprising:
 a) providing the fermentation medium comprising the carbon source and the limiting nutrient source;   b) adding the microorganisms to the fermentation medium;   c) adding an additional amount of the carbon source and limiting nutrient source to the fermentation medium to increase the biomass density of the fermentation medium to at least about 100 g/L on a dry cell weight basis;   d) adding an additional amount of the carbon source while limiting the amount of limiting nutrient source added to the formulation medium to induce lipid production by the microorganisms; and   wherein the microorganisms are of the order Thraustochytriales, and produce at least 15% by weight of the dry cell weight of the biomass as lipids.   
     
     
         24 . The biomass of  claim 23 , wherein the process further comprises e) recovering at least some of the lipids from the microorganisms. 
     
     
         25 . The biomass of  claim 23 , wherein the fermentation of the microorganisms produces lipids containing highly unsaturated fatty acids when the biomass density of the fermentation medium is at least 150 g/L on a dry cell weight basis. 
     
     
         26 . The biomass of  claim 23 , wherein the process produces lipids at an average rate of at least 0.5 grams lipids per liter of fermentation medium per hour fermentation. 
     
     
         27 . The biomass of  claim 23 , wherein the microorganisms are selected from the group consisting of  Thraustochytrium, Schizochytrium , and mixtures thereof. 
     
     
         28 . The biomass of  claim 23 , wherein the process produces on average at least 0.2 grams docosahexaenoic acid per liter of fermentation medium per hour fermentation. 
     
     
         29 . The biomass of  claim 23 , wherein the microorganisms produce lipids containing highly unsaturated fatty acids when the biomass density is at least 100 g/L on a dry cell weight basis. 
     
     
         30 . The biomass of  claim 23 , wherein the highly unsaturated fatty acids are selected from the group consisting of docosahexaenoic acid, docosapentaenoic acid, eicosapentaenoic acid, arachidonic acid and mixtures thereof. 
     
     
         31 . The biomass of  claim 23 , wherein the highly unsaturated fatty acids are eicosapentaenoic acid. 
     
     
         32 . The biomass of  claim 23 , wherein at least 25% of the lipids is docosahexaenoic acid. 
     
     
         33 . The biomass of  claim 23 , wherein the process produces lipids at an average rate of at least 0.5 g/L/hr and wherein at least 25% of the lipids is docosahexaenoic acid. 
     
     
         34 . The biomass of  claim 23 , wherein the carbon source comprises a carbohydrate. 
     
     
         35 . The biomass of  claim 23 , wherein the limiting nutrient source comprises a nitrogen source. 
     
     
         36 . The biomass of  claim 23 , wherein the pH of the fermentation medium is about pH 5 to about pH 11. 
     
     
         37 . The biomass of  claim 23 , wherein the fermentation medium is at a temperature of at least 20° C. 
     
     
         38 . The biomass of  claim 23 , wherein the microorganisms produce highly unsaturated fatty acids under aerobic conditions. 
     
     
         39 . An oil extracted from a biomass of any one of  claims 23 - 38 . 
     
     
         40 . The oil as recited in  claim 39 , wherein said oil is a crude oil extracted from the biomass without further processing. 
     
     
         41 . A feed product that contains a biomass of any one of  claims 23 - 38  or an oil of any one of  claims 39 - 40 . 
     
     
         42 . The feed product of  claim 41 , wherein said feed product is a feed or feed supplement. 
     
     
         43 . The feed of  claim 42 , wherein said feed is an animal feed. 
     
     
         44 . The feed of  claim 42 , wherein said feed is an aquaculture feed.