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uni'wissen 1-2013_ENG

ing a way to ensure the genetic stability of the bacterial cultures under industrial production conditions. It is still unknown how the microor­ ganisms react to stress, such as when tempera­ tures fluctuate wildly or not enough light penetrates through the dense cultures. Other difficulties include contamination by other or­ ganisms and spontaneous mutations that lead to a decrease in production rates. “We want to use artificial evolution to enrich and character­ ize cells that adapt particularly well to the pro­ duction conditions and yield the highest possible amount of ethanol, isoprene, or ethylene.” In ad­ dition, both of the Freiburg research groups are working on identifying so­called regulatory ele­ ments, which can improve the performance of the optimized strains. Last but not least, they are also studying factors that limit the yield of the finished product. “The key question is whether using cyanobac­ teria to produce ethanol can be made profitable,” says Wilde. The amount of ethanol that can be produced with light as an energy source cannot measure up to the alcohol yield from conven­ tional yeast fermentation. All the same, ethanol production could still prove to be a lucrative endeavor: Whereas yeast needs sugar to fer­ ment, cyanobacteria are less demanding, requir­ ing only the carbon from the CO2. A cost­benefit analysis reveals that the production method used in the project uses up much less resources Prof. Dr. Annegret Wilde studied microbiology at the University of Saint Peters- burg, Russia. She then spent 20 years conducting research in Berlin, first at the Institute of Technical Microbiology in Berlin- Buch, and from 1991 on at the Humboldt University. In 1994 she completed her dissertation on the photo- synthesis of cyanobacteria. From 1994 to 1998 she worked in a postdoc posi- tion at the Humboldt Uni- versity, before accepting a two-year scholarship from a German program promoting women in science. In 2001 the researcher accepted a position at the Department of Plant Bio- chemistry, where she completed her habilitation thesis on the molecular bi- ology of cyanobacteria. In 2008 she accepted a chair in microbiology at the Uni- versity of Gießen. In 2012 Wilde came to Freiburg as professor of molecular genetics. Her main research interests are the photosyn- thesis and genetics of cya- nobacteria. Photo: private Further Reading Mitschke, J./Georg, J./Scholz, I./Sharma, C. M./Dienst, D./Bantscheff, J./Voß, B./Steglich, C./Wilde, A./Vogel, J./Hess, W. R. (2011): An experimentally anchored map of transcriptional start sites in the model cyanobacterium Syn­ echocystis sp. PCC6803. In: Proceedings of the National Academy of Sciences of the United States of America 108/5, pp. 2124–2129. Wilde, A./Dienst, D. (2011): Tools for genetic manipulation of cyanobacteria. In: Peschek, G. A./Obinger, C./Renger, G. (Eds.) (2011): Bioenergetic processes of cyanobacteria. Dordrecht, pp. 685–703. Robertson, D. E./Jacobson, S. A./Morgan, F./ Berry, D./Church, G. M./Afeyan, N. B. (2011): A new dawn for industrial photosynthesis. In: Photosynthesis Research 107/3, pp. 269–277. than those used to produce conventional bio­ fuels. The photobioreactors can be installed on land that is unsuitable for farming. The salt­ tolerant bacterial strains are satisfied with sea­ water and thus use only little fresh water. The greenhouse gas CO2, which is pumped into the reactors, is available in the atmosphere in larger amounts than are beneficial to the environment. Finally, the light energy necessary for photosyn­ thesis comes for free from the sun. Will Annegret Wilde and her team achieve a breakthrough in energy production by the end of their three­year project? The microbiologist responds to this question with composure: “We don’t know that yet today. All I can say is that if we don’t try, we won’t find out the answer.” One-liter reactors in the lab: Researchers are ex- perimenting with bacterial cultures on a small scale in order to increase the ethanol yield. Photo: Anne- gret Wilde 11