Bacterial Metabolism & Evolution

Bacteria are ideal subjects for studying the mechanisms and effects of evolution in “real time”. Due to short generation times and the sheer number of cells, a rapid divergence of originally identical cells can be observed. When bacteria are exposed to selection pressures, i.e. environmental influences that affect cell survival (antibiotics, lack of nutrients, etc.), the first adaptation strategy is usually a change in gene expression. If the selection pressure is too strong to allow the survival of the bacteria by adapting gene expression, it is possible to select for suppressor mutants, i.e. bacteria that have a growth advantage in the presence of selective pressure due to spontaneous genetic changes (gene amplifications, point mutations, etc.) (Sandegren & Andersson, 2009).

In our research on bacterial metabolism, we utilize these adaptive mechanisms of bacteria to shed light on new relationships in metabolic pathways, their regulation and interconnectivity, and at the same time to investigate questions about the evolution and adaptability of bacteria.

Recently it was shown that both Bacillus subtilis and Escherichia coli are able to use an alternative metabolic pathway for the biosynthesis of the amino acid glutamate through genetic modifications under certain selective pressures (Mardoukhi et al., 2024; Schulz-Mirbach et al., 2022).

In our research, we are currently addressing the question of how the “classical” and “alternative” metabolic pathways for glutamate biosynthesis differ, why most bacteria use the “classical” metabolic pathway and what adaptations the “alternative” metabolic pathway requires of the bacteria.

Mardoukhi, M.S.Y., Rapp, J., Irisarri, I., Gunka, K., Link, H., Marienhagen, J., de Vries, J., Stülke, J. & Commichau, F.M. (2024) Metabolic rewiring enables ammonium assimilation via a non-canonical fumarate-based pathway. Microb Biotechnol. 17 (3): e14429.

Sandegren, L. & Andersson, D.I. (2009) Bacterial gene amplification: implications for the evolution of antibiotic resistance. Nat Rev Microbiol. 7: 578-588.

Schulz-Mirbach, H., Müller, A., Wu, T., Pfister, P., Aslan, S., Schada von Borzyskowski, L., Erb, T.J., Bar-Even, A. & Lindner, S.N. (2022) On the flexibility of the cellular amination network in E coli. eLife. 11: e77492.