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Press Release Ecofect - 25 march 2020

On The March 25, 2020

New Ecofect collaborative publication: The strategy of natural transformation of bacteria to resist recurring exposure to antibiotics

Natural transformation is the acquisition, controlled by bacteria, of extracellular DNA and is one of the most common mechanisms of horizontal gene transfer (HGT). HGT is the movement of genetic material between organisms other than by the transmission of DNA from parent to offspring. HGT plays an important role in the evolution of bacterial communities, and represent the primary process for the spread of antibiotic resistance.
The evolutionary function of natural transformation remains elusive, and two main roles have been proposed: (i) the new gene acquisition and genetic mixing within bacterial populations and (ii) the removal of infectious parasitic mobile genetic elements (MGEs). While the first one promotes genetic diversification, the other one promotes the removal of foreign DNA and thus genome stability, making these two functions apparently antagonistic. Using a computational model, this collaborative work between teams from the Biometry and Evolutive Biology Laboratory (LBBE, UMR CNRS 5558, Lyon 1 University) and the International Center for Research In infectiology (CIRI, Inserm U1111, CNRS, ENS Lyon, Lyon 1 University) and funded by the Ecofect LabEx under the ANTISELFISH project, show that intermediate transformation rates, commonly observed in bacteria, allow the acquisition then removal of MGEs. The transient acquisition of costly MGEs with resistance genes maximizes bacterial fitness in environments with stochastic to stresses such as antibiotic exposition. Thus, transformation would ensure both a strong dynamic of the bacterial genome in the short term and its long-term stabilization.

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Reference article:
Bacterial Transformation Buffers Environmental Fluctuations through the Reversible Integration of Mobile Genetic Elements
Gabriel Carvalho, David Fouchet, Gonché Danesh, Anne-Sophie Godeux, Maria-Halima Laaberki, Dominique Pontier, Xavier Charpentier, Samuel Venner. mBio, 11:2 | PDF