Compositions comprising eicosapentaenoic acid suitable for high purification
The invention relates to a microbial biomass composition produced from a heterotrophic fermentation whose fatty acid profile exhibits: an eicosapentaenoic acid (EPA) to arachidonic acid (ARA) ratio of about 11:1 or more; an EPA to total co-concentrating fatty acid ratio of about 8:1 or more, extract compositions, and methods of producing such compositions.
1. A method of producing a diatom, the method comprising:
a. cultivating diatoms in heterotrophic culture containing a nutrient solution comprising:
(i) a nitrogen source and an organic carbon source at an initial concentration of at least 0.5 M carbon,
(ii) a molar ratio of organic carbon to nitrogen of no higher than 30:1 (mol C:mol N), and
(iii) a non-limiting source of silicate at a concentration of 150 μM to 1.3 mM at all times during the culture; and
b. recovering the diatom from the heterotrophic culture,
wherein the cultivating conditions result in production of a diatom having at least 1.5% (w/w) of dry weight as eicosapentaenoic acid and an eicosapentaenoic acid to arachidonic acid ratio of at least 14:1.
2. The method of claim 1 wherein the diatoms are cultivated in heterotrophic culture in a fermenter.
3. The method of claim 2 wherein the cultivation comprises continuous fermentation.
4. The method of claim 1 wherein the diatoms comprise Nitzschia species.
5. The method of claim 1 wherein the cultivation is carried out at a temperature of from about 12° C. to about 35° C.
6. The method of claim 1 wherein the cultivation is carried out at a pH of from about 7.0 to about 8.7.
7. The method of claim 1 wherein said carbon source comprises glucose.
8. The method of claim 1 wherein said carbon source is selected from glucose, hydrolysed starch or hydrolysed whey.
9. The method of claim 1 wherein said nitrogen source is in the form of sodium nitrate or potassium nitrate.
10. The method of claim 1 wherein said nitrogen sources is supplemented with an amino-acid source.
11. The method of claim 10 wherein said amino-acid source is selected from corn-steep liquor, yeast extract, tryptone, peptones, lysine and glutamate.
12. The method of claim 1 wherein said silicate is in the form of sodium or potassium metasilicate.
13. The method of claim 1 wherein the nutrient solution comprises phosphorous in the form of phosphate.
14. The method of claim 13 wherein the molar ratio of organic carbon to phosphorus in the form of phosphate is no higher than 1250:1 (mol C:mol P).