Specifically, the project Tracking evolution of Life? - Laboratory evolution of a mesophilic microorganism from a thermophilic ancestor is based on the hypothesis that the first cells were not only anaerobic acetogenic bacteria (or methanogenic archaea) feeding on H₂ plus CO₂, but also heat-loving, with temperature optima >45°C (Weiss et al. 2016), the so-called thermophiles. We hypothesize that these thermophiles were ancient, and that the first microorganisms that live at moderate temperatures below 40°C were descendants of thermophiles. Although a lot of metabolic and cellular changes are required in response to lower temperatures, we also hypothesize that the adaptation to lower temperature may have happened fast. One could imagine a hyperthermophilic archaeon growing at 100°C detaching from a marine hydrothermal vent, entering the much cooler seawater and settling at a cold place. In the project, we try to mimic the evolution of a thermophile to a mesophile, using the acetogenic model organism T. kivui (T_OPT 66°C). Using a variety of approaches, for example by sequential passaging or by cold-shock experiments, we adapt T. kivui strains to lower growth temperatures (<50°C). Subsequently, we characterize their growth phenotype and metabolism, and analyze molecular changes in the genome or gene expression pattern using omics-technologies. Since the organism is genetically accessible (Basen et al. 2018), we are aiming at observing the effect of single and multiple mutations on the temperature-related phenotype in the future. During the course of the project, we hope to learn about the evolution of mesophily and the molecular changes required become a mesophile or a thermophile.

Team members involved:
Jun.-Prof. Dr. Mirko Basen
Dr. Maria Lehmann (2020 bis 2022)
M.Sc. Christoph Prohaska seit 2021