Missions

When practicing activities/hobbies in natural waters, the presence of pathogenic/opportunistic microorganisms or the presence of chemical compounds both constitute a health threat. Considered jointly, the cocktail of the two represents an additional threat linked to possible phenomena of synergy or additivity of their effects. More and more studies and observations in human health suggest that the pollution of our living environment affects our immune system and therefore increases our vulnerability to microbial infections. However, another paradigm carries the idea that pollution, at least certain pollutants, can also exacerbate the capacity of microorganisms to infect us. Indeed, current knowledge shows that organic pollutants can “stimulate” bacteria without killing them and in extenso make them activate/amplify biological factors known to be involved in their virulence (Thiroux et al. 2023). However, current knowledge on the risks generated by co-exposure to microbiological and chemical agents in an environmental context is still limited, in particular because of the multiple possible contexts.
The SAPROPHITE project wants to confront this paradigm in the context of natural waters due to their characteristic of bringing together microbiological and chemical agents, and of being frequented during aquatic activities/leisure. Thus, SAPROPHITE proposes to establish "if, and to what extent" the presence of organic pollution (OP, considering it as a complex cocktail of anthropogenic compounds and natural organic matter) exacerbates the virulence of bacteria and ultimately could increase the danger of bacterial infection associated with practices in aquatic environments, such as swimming.

Activités

The objective is to establish proof of this concept using model strains (Escherichia coli, Pseudomonas aeruginosa H103 and Salmonella enterica serovar. Typhimurium) and OPs “isolated” from sites where aquatic activities/hoobies are practiced; then to look for characteristics of the OP (mass compounds/ions) and determinants of the site (location, attendance, type of surrounding anthropogenic pressure, sampling period) correlated to this exacerbation effect.
The project is based on 14 sites located in the Vienne department and known for their summer attendance. 12 of these sites are controlled by the ARS and the two others are wild swimming sites. 1 unused and non-anthropized site also located in the Vienne at the Pinail national reserve will also be monitored as a “control” site. Several campaigns will be carried out from May to September to cover the period of site attendance + 1 campaign in January (off season). The research program will consist of:
1. determine the effect of PO on the virulence of model bacteria via the measurement of virulence factors (growth, mobility, specific genes) for each strain.
2. confirm the evidence of an exacerbation of virulence factors by infectivity tests on cell cultures by covering the range of exacerbation effect identified for each strain (ability of bacteria to adhere, invade and persist in cells of the host (epithelial cells and macrophages)).
3. Look for statistical links between the exacerbation effect (for each strain) the molecular markers of OP, the metadata of the site/sample, and the effect on the bacteria.

Compétences

The candidate must hold a doctorate in microbiology and demonstrate solid experience in in vitro culture techniques and molecular biology. Expertise in cell culture will be a plus for the position. Knowledge of the analysis of secondary metabolites by mass spectrometry will be appreciated. The candidate must also have excellent skills in organizing and working in a team and in collaboration with other teams to carry out this project.

Contexte de travail

Ecology and Biology of Interactions Laboratory, UMR CNRS 7267
Team Microorganisms Hosts Environments
University of Poitiers
Name of laboratory director: Jean-Marc Berjeaud
Team director name: Christine Imbert
Laboratory director telephone number: 05 49 45 40 06
Director email jean-marc.berjeaud@univ-poitiers.fr
https://ebi.labo.univ-poitiers.fr/microorganismes-hotes-environnements/