Dr. Kerstin Fiege

Archaeal/bacterial co-cultures as a model system for eukaryogenesis

The first eukaryotic cell is assumed to have arisen from a symbiosis of an archaeal cell, likely an Asgard archaeon, and a bacterial partner. As Asgard archaea are proposed to contain eukaryotic-like intracellular structures, it has been hypothesized that many eukaryotic proteins involved in regulated membrane contacts have their origins in archaea. Yet, little is known about the role of cell-to-cell contacts for the emergence of eukaryotes and which proteins and membrane structures were involved. Due to the lack of cultivated and genetically tractable Asgard archaea or closely relevant lineages, model systems of syntrophic interacting microorganisms can help to shed light on how  cell-to-cell interactions between different species arose and led to the emergence of the first eukaryotic cell.

Research project

In my project, I investigate the interaction between the sulfate-reducing bacterium Desulfovibrio vulgaris and the methanogenic archaeon Methanococcus maripaludis. Both organisms are strict anaerobes and capable of growing in mono culture but also in syntrophic co-culture. In these co-cultures, both species are dependent on the growth of the other one by exchanging molecules to gain energy and maintain a non-toxic environment. Initial and evolved co-cultures after several generations under syntrophic conditions are being analyzed by transcriptomics and proteomics to identify differentially expressed genes and proteins connected to cell-to-cell interactions with a focus on membrane proteins. These analyses are further complemented with lipid analyses to determine changes in the cell membrane of the syntrophic co-culture partners as a response to changes of membrane proteins.

To visualize the interaction between the two organisms different fluorescence microscopy methods are used. Besides imaging methods with fixed cells, like FISH, we aim to develop live-cell imaging under anaerobic conditions. For both organisms, methods for genetical modifications are available. Therefore, I am testing and establishing different fluorescence protein/peptide labels which can be used to genetically label proteins of interest during anaerobic growth. These fluorescence labels will be used for anaerobic live-cell imaging and investigating the role of interesting proteins during anaerobic cell growth.

This in-depth analysis of a model syntrophic co-culture will provide clues on how interdomain (Archaea/Bacteria) cell-to-cell interactions led to the emergence of the first eukaryotic cell. It will help to unravel the role of early archaea in it and which cellular structures have been involved in the fusion of two cells.

Research experience

2019-2020 Postdoc, Microbiology, Technische Universität Kaiserslautern, Germany

2013 Lab placement, "Subcellular localization of proteins involved in disulfide stress sensing and management in Bacillus subtilis",  Supervisor: Claes von Wachenfeldt, Lund University, Sweden

Education

2014-2019 PhD, "Function of two redox sensing kinases from the methanogenic archaeon Methanosarcina acetivorans", Supervisor: Dr. Nicole Frankenberg-Dinkel, Ruhr University Bochum and Technische Universität Kaiserslautern, Germany

2011-2014 M.Sc. Biology, Microbiolgy & Infection Biology, Technische Universität Braunschweig, Germany

2008-2011 B.Sc. Biology, Technische Universität Braunschweig, Germany

Researchgate

ORCID