Abstract:

An emerging function in the scientific literature, antibiotrophy is the bacterial capacity to metabolize antibiotics. Considered a bioremediation tool, it remains a health risk due to its association with antibiotic resistance. The first goal of this thesis was to study its dispersion within agrosystems contaminated with antibiotics during two coalescence events, i.e. manure spreading on the soil and its erosion towards the aquatic compartment. Experiments have shown the systematic invasion of the soil and sediment bacterial communities by the antibiotroph Microbacterium sp. C448 when sulfamethazine is present but not necessarily mineralized. The antibiotic would have a double function towards this strain: to decrease the competition by its biocidal action on the community and to constitute an exclusive nutritive source when necessary. This work also reports the isolation of two new antibiotrophic strains from natural river sediments that are phylogenetically and functionally close to those already known. This highlights the underestimated ubiquity of the antibiotrophy function and its probable recent widespread dispersal. Addressing the theme of bacterial dispersal in general, these experiments have highlighted bacterial transfers between different environmental compartments that can be influenced by antibiotic contamination, thus calling for the need to focus on the specific case of antibiotic-resistant bacteria. 

Jury

Lise BARTHELMEBS et Gwenaël IMFELD  rapporteurs 

Jean MARTINS et Agnès RICHAUME examinateurs

Marion DEVERS-LAMRANI et Stéphane PESCE Co-directeur de thèse