Ir DMM (Dorinde) Kleinegris: "Milking of microalgae revisited"

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29 Oct 2010 16:00 - 29 Oct 2010 17:30
Unit: Wageningen University
Location: Aula, building 362, Gen. Foulkesweg 1, Wageningen
Organisation: Wageningen University
Promotor: prof.dr.ir. R.H. Wijffels (Bioprocess Engineering)
Co Promotor: dr ir MGJ Janssen , dr WA Brandenburg

 The microalga Dunaliella salina is used for the production of beta-carotene, an orange pigment also known as pro-vitamin A. Currently this alga is cultivated in open ponds in sunny regions (such as Israel and Australia). After harvesting of the algae, the beta-carotene is extracted. This two-step process (the cultivation of algae and the extraction of the beta-carotene) can also be performed in one step in a closed cultivation system. The algae are then cultivated in the proximity of an organic solvent that is being used for extraction. The cells lose their beta-carotene to this solvent.

We have studied the mechanism of the transfer of beta-carotene from the cell to the solvent. If the mechanism is known, the process can be made more efficient (and thus cheaper). Besides, we would like to use this process principle for other algae for the production of lipids (for example for the production of biodiesel).
We found out that the cells do not lose the beta-carotene and reproduce it (milking), as was thought before, but that part of the cells dies and falls apart into small pieces. Consequently, the beta-carotene comes free and dissolves in the organic solvent. The rest of the cells stay alive and reproduce. Because cell death and cell growth are in equilibrium, the number of cells remains constant. The production of beta-carotene can be increased by increasing the rate of growth and cell death. This is possible by increasing the contact area between the cells and the solvent.

» More information: Research on microalgae within Wageningen UR 
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