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) by culturing heterotrophic microalgae of the class Dinophyceae in a culture medium, wherein the medium comprises:
(a) chloride ion at a concentration of less than or equal to about 2 g/l; and
(b) potassium ion at a concentration of greater than or equal to about 0.25 g/L;
wherein the microalgae produces at least about 0.04 g DHA per 10 9 cells.
2. The method of claim 1 , wherein the microalgae is of the genus Crypthecodinium.
3. The method of claim 1 , wherein the microalgae is of the species Crypthecodinium cohnii.
4. The method of claim 1 , wherein the concentration of the chloride ion is less than or equal to about 1.0 g/l.
5. The method of claim 1 , wherein the concentration of the chloride ion is less than or equal to about 0.3 g/l.
6. The method of claim 1 , wherein the concentration of the potassium ion is greater than or equal to about 0.4 g/L.
7. The method of claim 1 , wherein the concentration of the potassium ion is greater than or equal to about 0.8 g/L.
8. The method of claim 1 , wherein a source of the potassium ion is potassium sulfate.
9. The method of claim 1 , wherein medium further comprises sodium ion at a concentration of from about 1 g/L to about 8 g/l.
10. The method of claim 9 , wherein the concentration of the sodium ion is from about 1.5 g/l to about 5 g/L.
11. The method of claim 9 , wherein a source of sodium ion is sodium sulfate.
12. The method of claim 9 , wherein the concentration of the potassium ion is about 0.8 g/L and the concentration of the sodium ion is about 3.2 g/L.
13. A biomass produced by the method of claim 1 .
14. The method of claim 1 , wherein the microalgae produces at least about 0.10 g DHA per 10 9 cells.
15. The method of claim 1 , wherein the microalgae produces at least about 0.20 g DHA per 10 9 cells.
16. The method of claim 1 , further comprising recovering a DHA-containing lipid from the microalgae.
17. A method of producing docosahexaenoic acid (DHA) by culturing heterotrophic microalgae of the class Dinophyceae in a culture medium, wherein the medium comprises:
(a) chloride ion at a concentration of less than or equal to about 2 g/l;
(b) potassium ion at a concentration of greater than or equal to about 0.25 g/L; and
(c) sodium ion in a ratio of less than or equal to about 27:1 wt:wt sodium:potassium;
wherein the microalgae produces at least about 0.04 g DHA per 10 9 cells.
18. The method of claim 17 , wherein the microalgae is of the genus Crypthecodinium.
19. The method of claim 17 , wherein the microalgae is of the species Crypthecodinium cohnii.
20. The method of claim 17 , wherein a source of the potassium ion is potassium sulfate.
21. The method of claim 17 , wherein a source of sodium ion is sodium sulfate.
22. The method of claim 17 , wherein the concentration of the chloride ion is less than or equal to about 1.0 g/l.
23. The method of claim 17 , wherein the concentration of the chloride ion is less than or equal to about 0.3 g/l.
24. The method of claim 17 , wherein the concentration of the potassium ion is greater than or equal to about 0.4 g/L.
25. The method of claim 17 , wherein the concentration of the potassium ion is greater than or equal to about 0.8 g/L.
26. The method of claim 17 , wherein the sodium:potassium ratio is less than or equal to about 15:1 wt:wt.
27. The method of claim 17 , wherein the concentration of the potassium ion is about 0:8 g/L and the sodium:potassium ratio is about 4:1 wt:wt.
28. A biomass produced by the method of claim 17 .
29. The method of claim 17 wherein the microalgae produces at least about 0.10 g DHA per 10 9 cells.
30. The method of claim 17 wherein the microalgae produces at least about 0.20 g DHA per 10 9 cells.
31. The method of claim 17 further comprising recovering a DHA-containing lipid from the microalgae.