"Long bacterial cell" phenotype in the Long-Term Evolution Experiment (LTEE) on Escherichia coli
Year: 2024
Type: conference-paper
Abstract: Changes in bacterial length are related to the disruption of biological processes such as chromosome replication, cell division, cell elongation, cell wall assembly, and growth rate. The Long-Term Evolution Experiment (LTEE), initiated by R.E. Lenski in February 1988, aims at studying the long-term evolution of Escherichia coli in a controlled environment: two strains (~ 2 μm long), respectively REL606 (Ara-: unable to use arabinose as a carbon source) and REL607 (Ara+: REL606 revertant capable of arabinose degradation) were used to found 12 populations, 6 flasks inoculated with REL606 and 6 others, with REL607. The 12 flasks contained a minimal medium supplemented with only 25 mg/L glucose (DM25). Since 1988, one percent of each of these 12 flasks has been and is still transferred every 24 hours into a set of 12 clean flasks containing fresh medium. This technically simple experiment has generated, so far, more than 76,000 bacterial generations (https://the-ltee.org/) that have not been challenged by any antibiotic or immune response for more than 32 years. The 12 populations have rapidly adapted to their stringent environment by increasing their fitness, their growth rate and their volume. However, 2 populations, namely Ara-3 and Ara-5, have gradually developed an exceptional length (up to 50 m) at 50,000 generations of evolution (50K). We have identified mutations affecting the divisome, the elongasome, both the cell wall and the lipid biosynthesis pathways that may be linked to the observed phenotype. We have complemented both Ara-3, 50K and Ara-5, 50K with plasmids that allow the independent expression of 5 of the divisome proteins, restoring partially of completely the regular E. coli length. We have validated biochemically that membrane lipids are modified in the evolved populations. We are now re-constructing the ancestral alleles of a few mutations in the genome of both Ara-3, 50K and Ara-5, 50K to validate the role of the identified mutations in the “Long bacterial cell” phenotype.
Source: HAL
Institutions: Translational Innovation in Medicine and Complexity, Centre Hospitalier Universitaire de Grenoble, Institut de Biologie Structurale, Établissement Français du Sang, Université Grenoble Alpes, Centre National de la Recherche Scientifique, Inserm, Institut pour l'avancée des biosciences, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, CEA Grenoble, Laboratoire Physiologie Cellulaire & Végétale
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7205348188