Production of high levels of DHA in microalgae using modified amounts of chloride and potassium
View Patent ↗Methods for production of highly unsaturated fatty acids by marine microorganisms, including the heterotrophic marine dinoflagellate Crypthecodinium , using low levels of chloride ion are disclosed. Specifically, methods of increasing production of highly unsaturated fatty acids by marine microorganisms while growing in low chloride media by manipulating sodium ion and potassium ion levels. The invention also relates to methods of production of highly unsaturated fatty acids by marine organisms at low pH levels, and includes methods for generation of low pH tolerant strains.
1. A method of producing docosahexaenoic acid (DHA), comprising:
culturing a heterotrophic microalga in a culture medium, wherein the culture medium comprises:
chloride ions at a concentration of less than or equal to 3 g/L;
potassium ions at a concentration of 0.95 g/L to 10 g/L;
wherein the culture medium further comprises sodium ions, wherein a ratio of sodium ions to potassium ions is less than or equal to 27:1; and
recovering DHA-containing lipid from the microalga, wherein the microalga produces at least 0.04 g DHA per 10 9 cells.
2. The method of claim 1 , wherein the concentration of chloride ions is less than or equal to 2 g/L.
3. The method of claim 1 , wherein the concentration of chloride ions is less than or equal to 1 g/L.
4. The method of claim 1 , wherein the concentration of chloride ions is less than or equal to 0.3 g/L.
5. The method of claim 1 , wherein the concentration of potassium ions is 0.95 g/L to 4 g/L.
6. The method of claim 1 , wherein the concentration of potassium ions is 0.95 g/L to 3 g/L.
7. The method of claim 1 , wherein the concentration of potassium ions is 0.95 g/L to 2.4 g/L.
8. The method of claim 1 , wherein the concentration of potassium ions is 0.95 g/L to 2 g/L.
9. The method of claim 1 , wherein the sodium ions are at a concentration of 1 g/L to 8 g/L.
10. The method of claim 1 , wherein the sodium ion is ions are at a concentration of 1 g/L to 8 g/L, and wherein the pH is less than or equal to 5.
11. The method of claim 1 , wherein the sodium ion is ions are at a concentration of 1.5 g/L to 5 g/L, and wherein the pH is 4.5.
12. The method of claim 1 , wherein a source of potassium comprises potassium sulfate.
13. The method of claim 1 , wherein the microalga produces at least 0.10 g DHA per 10 9 cells.
14. The method of claim 1 , wherein the microalga produces at least 0.20 g DHA per 10 9 cells.
15. The method of claim 1 , wherein the ratio of sodium ions to potassium ions is less than or equal to 15:1.
16. The method of claim 1 , wherein the ratio of sodium ions to potassium ions is less than or equal to 4:1.
17. The method of claim 1 , further comprising recovering DHA from the DHA-containing lipid.
18. The method of claim 1 , wherein the microalga is of the genus Dinophyceae .
19. The method of claim 1 , wherein the microalga is of the genus Crypthecodinium .
20. The method of claim 1 , wherein the microalga is of the species Crypthecodinium cohnii .