UFZ-Seminar "Wasser und Umwelt"
Montag, 14. Dezember 2015, 15.00Uhr
Seminarraum, Brückstraße 3a, 39114 Magdeburg
Liisa K. Rihko-Struckmann
Group of Process Systems Engineering, Max Planck Institute for Dynamics of Complex
Green Microalgae – Cell factories for the production of chemicals and fuels?
Photosynthetic microorganisms such as green microalgae are promising option for the production of
chemicals and fuel compounds from renewable source. These microorganisms are capable of
synthesizing a wide range of compounds from sunlight and carbon dioxide at higher volumetric and
areal productivities compared to terrestrial crops. From a commercial perspective, carotenoid pigments
from natural origin are of great industrial relevance. Dunaliella salina is an example of microalgae
species, which is commercially cultivated in saline open ponds for the production of natural carotenoids.
We have carried out the mathematical modelling supported by lab-scale cultivations of D.salina for the
b-carotene production . The modeling and control of micro-organic cultivations is a very challenging
task, because the biological cell populations represent a complex dynamic system. Additionally,
biological systems exhibit strong variability in the phenotype, e.g. metabolite dynamics, which renders
difficult experimental probing for model identification. The profile likelihood approach was applied,
because it characterizes the model parameters and facilitates the development of predictive models.
The understanding of cellular up-/downstream interlinkages provides the basis for optimization on unit
as well as on plant level. On the upstream side, accumulation of natural b-carotene in D. salina is a
consequence of growth under adverse conditions (e.g. high light intensities or nutrient depletion). The
environmental stress factors triggers a cellular response, which ultimately leads to storage of the highvalue
compound b-carotene in intracellular oil globules. However, the underlying cellular stress
response can result in impaired growth or even cell death and thus negatively affect process
robustness. On the downstream side, the initial, extreme low concentration of microalgal cells creates a
challenge for existing separation and extraction techniques. Some experimental techniques of
flocculation have been compared and analyzed to declare the potential to cope with product purification
and ultimate extraction of b-carotene in D. salina. For that reason chemical and physical flocculation
methods are investigated as a ß-carotene harvesting approach for microalgae in comparison to the conventional method of centrifugation .
 M. Fachet, R. J. Flassig, L. K. Rihko-Struckmann and K. Sundmacher, A dynamic growth model of
Dunaliella salina: Parameter identification and profile likelihood analysis, Bioresource Technol. 173 (2014) 21-31.
 K. Pirwitz, L. K. Rihko-Struckmann, and K. Sundmacher, Comparison of flocculation methods for
harvesting Dunaliella. Bioresource Technol. 196 (2015)145-152.
Dr. Désirée Dietrich
Tel.: 0391 810-9101
Fax: 0391 810-9111