Work context: This thesis project is funded by the 80PRIME programme of the CNRS.

The Centre Émile Durkheim (UMR5116) is a generalist social science laboratory with about 70 full members, mainly sociologists and political scientists, but also lawyers, economists and historians, as well as research support staff, and as many PhD students. The approaches are pluralistic and the investigations cover subjects as varied as educational inequalities, political institutions and behaviour, political economy, health, defence, corruption, social and solidarity economy, urban sociology, migrations - to name but a few - and cover various cultural areas. The themes of the laboratory evolve according to the interests of its members, and questions relating to the ecological transition are now a strong point of the programmes undertaken.

MIVEGEC is a biology laboratory that is particularly interested in the ecology and evolution of health. The PhD student will be more specifically involved in the Perturbation-Evolution-Virulence department in the "Virostyle" team, which is interested in the selective pressures exerted on viruses and their hosts with experimental evolutionary approaches on different viruses infecting humans (papillomavirus, dengue & hepatitis), plants (nanovirus) or bacteria (bacteriophages). Virostyle currently comprises 6 permanent researchers, 2 non-permanent research engineers, 2 post-docs and 5 PhD students (not including master students). The bacteriophage group currently includes 2 PhD students and 1 post-doc with whom the MITI PhD student will work in close collaboration (experiments, bio-info analysis, etc), while participating in the weekly meetings of the group and of the department (presentation of results, journal club, etc).

Because of their biocidal abilities, bacterial viruses ("bacteriophages") can be used in many bioremediation projects (therapy or biocontrol), possibilities that are arousing growing interest, particularly because of the loss of effectiveness of antibiotics. In this context, experimental evolution using the natural capacity of bacteriophages to spontaneously modify their biological properties constitutes a promising angle for increasing their sanitary performance. However, the history of antibiotic use leads us to consider microbial mediations with great caution: microbes act and react, as shown by the widespread development of bacterial antibiotic resistance. Before any development of bacteriophages for health use, fundamental research is therefore necessary to better understand the evolutionary interactions between bacteriophages and bacteria. Furthermore, interdisciplinary work combining social sciences and life sciences seems to us to be essential to grasp these problems as they develop in order to better understand both the biological and social issues of this emerging practice. Through an ethnography of scientific practices, the aim will be to develop a theoretical and practical analysis of the domestication of bacteriophages carried out during experimental evolution sessions in the laboratory, to pay attention to the way in which this knowledge is produced, to the issues at stake in this production, but also to reflect on the conditions and possible consequences of the use of this knowledge once it has been produced.

In this context, the doctoral student will carry out a laboratory ethnography within Rémy Froissart's team. This ethnography will be based on several months of participant observation, during which the PhD student will learn to manipulate phages and bacteria and to understand the foundations of experimental evolution in different application frameworks (human, plant health & biocontrol). He/she will be co-supervised by Rémy Froissart and Charlotte Brives. Regular interviews will also be conducted with members of the Montpellier team (PhD students, post-docs, technicians and other researchers) and the network of scientists working in collaboration with us on similar topics, analysing practices, objectives and potential opportunities. This ethnography will be linked to a broader study of research networks and existing initiatives on the use of phages, work that has been carried out for several years by Charlotte Brives, in collaboration with researchers from the Phages.fr network.