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Annegret Wilde – jetlagged cyanobacteria

Sleep-deprived bacteria? Prokaryotes that move towards the light? Yes, they actually exist, as demonstrated by Prof. Dr. Annegret Wilde from the Institute of Molecular Genetics at the University of Freiburg. For the past 15 years Wilde has been studying the requirements and capabilities of cyanobacteria and she was appointed chair for molecular genetics at the University of Freiburg in August 2012.

Prof. Dr. Annegret Wilde knows cyanobacteria inside out. © private

Annegret Wilde was born in former East Berlin in 1966 and developed an early interest for biology whilst at school, partly due to a biology teacher who got her interested in the molecular basis of biology. “The fact that I ended up working in the field of microbiology is probably due to my interest in smaller organisms,” Wilde says, going on to add, “I know of many students who studied biology because they liked horses and dogs. But this was not the case with me.” 

Back then in East Germany, education was determined by national economic needs and objectives; the number of students and what they could specialise in was determined by the state’s economic plan. Young East Germans who wanted to study biology therefore had a fairly limited chance of actually obtaining one of the very few places. Wilde decided to study in Russia, which at that time was not that popular. Looking back, she sees her stay in St. Petersburg as the best thing that could have happened to her. “The quality of the molecular biology and genetics study programme was excellent,” says Wilde. “I did my microbiology degree in St. Petersburg and returned to Berlin in 1990 (ed. note: 1990 was the year of German reunification). I had no problems at all keeping up with my colleagues as far as the science was concerned.” 

On her return she began working as a scientific assistant in a microbiological research institute in Berlin-Buch, a position she was guaranteed before she went to Russia. She was fortunate that the job was still available. “Many other people were less fortunate because the institutions where they were supposed to work no longer existed,” Wilde recalls. 


Motivation and mentoring

Synechocystis colonies are capable of phototactic movement. © Prof. Dr. Annegret Wilde, University of Freiburg

When the research institute in Berlin-Buch was closed down, Wilde applied for a so-called NaFöG grant (Berlin funding scheme for graduates) which enabled her to do a doctoral thesis on the evolutionary relationship of chloroplasts and cyanobacteria in Prof. Dr. Thomas Börner’s laboratory at Humboldt University. She received her PhD in 1994 and continued as a postdoctoral fellow in Börner’s laboratory. She returned to Börner’s laboratory after the birth of her son. 

In 2001, she became assistant professor in the Department of Plant Biochemistry at Humboldt University and in 2006 habilitated and received her venia legendi in molecular biology. In 2008, she became professor for microbiology at the University of Giessen. Although the scientific environment in Giessen suited her interests quite well, she nevertheless decided to accept the position of professor for molecular genetics at the University of Freiburg in order to focus specifically on bacterial genetics. She enjoys the academic landscape in Freiburg, especially the strong focus on phototrophic microorganisms in the Department of Microbiology and in the Genetics & Experimental Bioinformatics laboratory headed up by Prof. Dr. Wolfgang Hess with whom she had already previously worked. 

Wilde describes the working atmosphere in the group of her former supervisor, Prof. Börner, as a key moment in her career. As she sees it, Börner did a great job in motivating his staff and students and showing them that science was fun; many of her former colleagues in the Berlin-Buch laboratory stayed in science for this reason. “And this is also why I am here today,” said Wilde. “Ten of Börner’s former students have since become professors, four of whom are women.” 

The second important milestone in Wilde’s career was the mentoring programme ProFiL (Professionalisation of Women in Research and Teaching: Mentoring – Training - Networking), initiated by the three Berlin universities in 2004 with the goal of supporting highly qualified women scientists in their quest to obtain a full professorship. Wilde is convinced that she would not have become a professor without this programme, its mentors, workshops and the opportunity to exchange information with other like-minded women scientists.

Cyanobacteria – a rather exotic subject

When Prof. Wilde started focussing on cyanobacteria, research into these tiny unicellular organisms was still considered a rather exotic subject. Nobody took the subject really seriously and hardly any funding was available for cyanobacterial research projects. Moreover, microbiologists refused to regard photosynthetic bacteria as bacteria and plant scientists did not see them as algae. Despite the slow start, the scientific view of cyanobacteria has changed fundamentally in recent years. Cyanobacteria have grown in importance, especially due to the discovery that they can be used to produce biofuels. In cooperation with Algenol Biofuels Germany GmbH, Wilde and her 10-member team are looking for ways to produce ethanol with cyanobacteria on the industrial scale. The scientists have chosen the cyanobacterium Synechocystis sp. strain PCC 6803 for their investigations and are specifically interested in the bacteria’s genetic systems and molecular regulatory mechanisms. 

Advancing like Spider-Man

Synechocystis colonies are capable of phototactic movement. © Prof. Dr. Annegret Wilde, University of Freiburg

Wilde finds phototaxis a particularly interesting phenomenon. “Cyanobacteria can move towards light, and they do so with so-called pili. Pili are protein nanostructures that are also found in pathogenic organisms.” Cyanobacteria use these appendages in order to exchange information with other bacteria as well as to attach to and move along surfaces. 

“They advance a bit like Spider-Man, but much slower,” jokes Wilde. Cyanobacteria can cover a distance of one centimetre per week, but that is more than enough as the biofilms into which they are embedded are only one to two millimetres thick. Reaching the surface where they can achieve a better light yield does not require a longer swim. “When we started focussing on phototaxis a few years ago, many scientists laughed at us,” recalls Wilde. “The kind of questions we got were: why do the bacteria need to move around, and why do they move so slowly?” It is now known that cyanobacteria have different photoreceptors with which they can discern different light colours; they move towards long-wavelength red and green light where they find optimal photosynthetic conditions. UV light damages the bacteria, so they move away from it. Wilde and her team are studying the bacteria’s movement in order to obtain in-depth insights into the underlying molecular mechanisms. They manipulate photoreceptors to change the motility of the bacteria, to name but one example of their research activities.

Circadian clocks

Wilde’s team is studying the molecular mechanisms of blue-green algae (A. Wilde: 2nd from the right, front row). © Prof. Dr. Annegret Wilde, University of Freiburg

Another exciting thing about cyanobacteria is that they are probably the only prokaryotes with a circadian clock. They follow a 24-h rhythm which they can maintain over several days under constant light conditions despite the fact that they divide more than once during this period. The cyanobacterial clock consists of just three proteins, one of which is phosphorylated and dephosphorylated during the course of a cycle. When this rhythm is disturbed, for example by phase-delayed light and dark stimuli, the cyanobacteria suffer from jetlag and need to synchronise their rhythm with the environment again. But what do these bacteria need a circadian clock for? “Even before the sun rises, the bacteria can already transcribe their photosynthesis genes and are ready for action as soon as the first light rays appear,” Wilde explains. 

“I think university courses should be concentrating to a greater extent on the green sciences,” said Wilde highlighting her vision for the future. However, considering the current food and fuel situation, the future is already on our doorstep.

Further information:

Prof. Dr. Annegret Wilde
Institute of Biology III
University of Freiburg
Schänzlestr. 1
79104 Freiburg
Tel.: +49 (0)761/203-97828
E-mail: annegret.wilde(at)biologie.uni-freiburg.de

Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/annegret-wilde-jetlagged-cyanobacteria