News aus der Fakultät

2 PhD Positions in Geomicrobiology/Microbial Ecology

Department of Geosciences, Center for Applied Geosciences

The research group for Geomicrobiology/Microbial Ecology at the Center for Applied Geosciences at the University of Tübingen is looking for 2 PhD students working on

"Genetic and physiological mechanisms of microbial iron oxidation"


Project description
Under anoxic conditions, Fe(II) is relatively stable, and anaerobic nitrate-reducing and anoxygenic phototrophic microorganisms are mainly responsible for its oxidation to Fe(III). The molecular mechanism and cellular localization of anaerobic Fe(II) oxidation is largely unknown. Genetic and electron-microscopic studies suggest that Fe(II) oxidation occurs in the periplasm and/or at the cell surface. While Fe(II) is relatively soluble at neutral pH, Fe(III) is poorly soluble and is therefore rapidly precipitating as Fe(III) mineral after its formation from Fe(II). Anaerobic Fe(II)-oxidizing microorganisms are therefore challenged by the formation of a potentially harmful metabolic product, i.e., Fe(III) minerals. The Fe(III) ions and Fe(III) minerals are expected to sorb to the cell surface, leading to cell encrustation that could prevent or limit the availability of photons (in case of the phototrophs), nutrients and substrates, thus leading to reduced cell metabolism or even cell death. The focus of this research project will be the identification of genetic/physiological mechanisms and strategies used by neutrophilic, anaerobic Fe(II)-oxidizers (phototrophic and nitrate-reducing) to survive and and/or prevent cell encrustation.

Project 1 will address the question: How do Fe(II)-oxidizing bacteria survive and/or prevent the formation of Fe(III) mineral crusts during Fe(II) oxidation? In this project microbial cultures of different nitrate-reducing and phototrophic Fe(II)-oxidizers will be analyzed using physiological, geochemical, spectro-,  and electron microscopy techniques.

Project 2 does focus on the genetic components and mechanisms involved in neutrophilic, nitrate-dependent iron oxidation. By random mutagenesis mutants deficient in iron oxidation shall be identified. In defined growth experiments these mutants will then be further characterized using analytical microscopy techniques and whole genome-based transcriptomic/proteomic approaches.

We offer PhD positions in an interdisciplinary, international, young and dynamic team of microbiologists, geochemists, and molecular biologists. This position provides an opportunity to bring in the candidate’s own creativity and self-responsibility. You will be trained in various state-of-the-art laboratory techniques and learn how to discuss and present experimental data to an audience of scientists with diverse educational background. The two open PhD positions will be integrated into a newly established, DFG-funded Research Training Group (RTG, Graduiertenkolleg) at the University of Tübingen entitled "Molecular principles of bacterial survival strategies". The RTG is a collaborative PhD program involving 9 professorial and 4 independent junior research groups in Tübingen. The program is a joint effort of research groups studying bacterial stress physiology and survival strategies from various environmental and medical perspectives. The new RTG will provide an excellent platform for the development of synergistic research concepts and post-graduate training.

You should have a background in bacterial genetics, microbiology, molecular biology, geomicrobiology, geoecology or biogeochemistry and like working in a team in an interdisciplinary research group. Applicants should have good communication skills and be highly motivated and committed to pursuing interdisciplinary research particularly focusing on environmental issues. Good computer and language skills (English) are imperative. The PhD positions will be funded by fellowships of the Research Training Group "Bacterial Survival Strategies" at the University of Tübingen. The positions will be open until qualified candidates are identified. The employment will be arranged by the administration of the University of Tübingen. We particularly encourage female applicants to apply for this position. Disabled persons will be preferred in case of equal qualification.

Please send your application indicating your interest in PhD position 1 "Physiological and cellular processes" by e-mail to Prof. Andreas Kappler (andreas.kappler[at] or in PhD position 2 "Genetic mechanisms" to Dr. Sebastian Behrens (sebastian.behrens[at] at University of Tübingen. Application deadline is July 15th 2011.