MICROBIOPLAST

This research project aims to explore the interactions between microplastics in the soil, the associated microbial communities, and a terrestrial living organism. The snail will be used as a critical trophic link between soil and higher consumers. The core hypothesis is that soil microorganisms adhere to microplastics, giving them a role as vectors for potentially pathogenic microbes that enter the food chain. Furthermore, this adhesion may alter microbial resistance properties, affecting their susceptibility to decontamination treatments and competition with other bacterial populations such as native microbiota. Testing these hypotheses will clarify how microplastics influence microbial ecology and resistance, with implications for environmental safety and biotechnological applications.

Objectives of the proposal:

• characterizing microbial colonization of soil plastisphere with focus on spore-forming bacteria, particularly Bacillus genus, determining whether microplastics preferentially select for these resistant organ-isms.

• assessing evolution of plastisphere bacterial populations upon in vivo exposure to snail gut microbiota.

• assessing the resistance of a carefully selected Bacillus strain (spores and vegetative cells) present in the soil plastisphere to physical decontamination treatments (high temperature, UV).

• determining the fate of these Bacillus spores following snail ingestion of contaminated microplastics.

The project will employ cutting-edge analytical techniques: fluorescence microscopy, O-PTIR (Optical Photother-mal Infrared) and Raman spectroscopy for submicron-resolution characterization of microplastics and biocorona composition. These advanced spectroscopic methods enable analysis of small microplastics (<100 μm) most rel-evant for biological uptake. High-throughput molecular characterization of plastisphere communities will be used to identify taxa enriched on microplastics and functional genes related to resistance.

The proposal directly integrates into the Harmi working package 1. It addresses fundamental questions about how anthropogenic pollutants (microplastics) shape microbial dispersal across environment. It will strength regional scientific infrastructure by fostering collaboration between three research units in Bourgogne-Franche-Comté (UMR Agroécologie, UMR Chrono-environnement, UMR PAM) and two HARMI-recognized platforms (DI-maCell, GenoSol). This integration valorizes substantial regional investment in these platforms while enhancing their visibility and demonstrating their synergistic capabilities.