Prof. Dr. Lotte Søgaard-Andersen
Bacterial development & differentiation
Lotte Søgaard-Andersen (born 1959)
M. Sc. thesis (Molecular biology), University of Odense, 1984
Medical Doctor, University of Odense, 1988
Visiting scientist, Institut Pasteur, Paris, 1990
PhD (Molecular biology), University of Odense, 1991
Post-doc, University of Odense, 1991
Assistant professor, University of Odense, 1992
Visiting scientist, Stanford University, 1994
Associate professor, University of Southern Denmark, 1996
Professor, University of Southern Denmark, 2002
Director and Head of the Department of Ecophysiology at the MPI in Marburg, since 2004
Professor for Microbiology at the Philipps-Universität Marburg, since 2008
Group leader at the department
Research area: Bacterial adaptation and differentiation
The overall goal of our research is to unravel the mechanisms that allow bacteria to adapt and differentiate in response to changes in the environment. Bacteria have evolved at least three strategies that allow them to cope with such changes. One strategy centers on changes in gene expression ranging from changes in the expression of relatively few genes to changes in the expression of large numbers of genes culminating in cell differentiation. A second strategy centers on changes in the motility behavior of cells. Finally, a third strategy centers on changes to the cell cycle. To implement these strategies bacterial cells have to process vast amounts of information and then generate the appropriate output response. Information processing is carried out by complex networks of signal transduction proteins. A challenging problem in bacterial adaptation and differentiation is to understand how these protein networks are organized in space and time to allow the ordered execution of various tasks.
We use Myxococcus xanthus as a wonderful model system to study bacterial adaptation and differentiation. In particular, we study the signal transduction pathways and networks governing differentiation, motility and the cell cycle. In parallel approaches, we aim to understand how molecular machineries involved in motility and cell division function.
The model organism: Myxococcus xanthus
Cells of Myxococcus xanthus self-organize into two distinct biofilms. In the presence of nutrients, the motile, rod-shaped cells grow and divide, and if present on a solid surface, they form cooperatively feeding colonies in which cells at the edge spread outwards. In response to starvation, growth ceases, cells change their motility behavior and a developmental program is initiated that culminates in the formation of multicellular fruiting bodies. After 24 hrs of starvation, nascent fruiting bodies have formed and the cells that have accumulated inside fruiting bodies differentiate to diploid spores. Thus, fruiting body formation is a wonderful model system to analyze how bacteria coordinate changes in motility behavior, gene expression and cell cycle regulation in response to an environmental stress signal.
The overall goal of our research is to understand how M. xanthus responds to starvation with the formation of spore-filled fruiting bodies. To this end, we study at the molecular and cellular level as well as at the theoretical level
M. xanthus belongs to the myxobacteria that are the only bacteria that cope with starvation with the formation of fruiting bodies. Amazingly, the fruiting bodies formed by different myxobacteria have very different shapes varying from haystack-shaped (as in the case of M. xanthus), stalked, coral-shaped to tree-shaped. We use genome sequencing, comparative genomics and transcriptomics to understand the genetic basis underlying differences in fruiting body morphology as well as the evolution of the genetic program(s) for fruiting body formation.
Finally, in a top-down synthetic (micro)biology approach, we also use the lessons learned from studying naturally occurring bacteria to generate modules for synthetic and streamlined cells
We use a suite of experimental techniques including molecular genetics, biochemistry with protein purification and their in vitro characterization, cell biology with live cell-imaging, proteomics, de novo sequencing of myxobacterial genomes, comparative genomics, and transcriptomics using RNAseq.