Ph.D thesis of Quentin Pruvost (2026-2029)

They are tiny, invisible to the naked eye, but incredibly effective: small biological bubbles capable of neutralizing dangerous bacteria and communicating with our immune system. They sound like something straight out of a science fiction novel... yet they come from the very real world of microbes found in our food!

Some of these bacteria or yeasts, known for their benefits in digestion or food preservation, naturally produce antimicrobial compounds. They prevent unwanted bacteria—such as Salmonella, Listeria monocytogenes, or E. coli—from growing, much like plants that repel pests with natural substances. But instead of simply cultivating them in food, a new strategy involves exploiting their extracellular vesicles: tiny capsules that they release, loaded with active molecules (proteins, RNA, peptides, etc.).

These extracellular vesicles function like smart biological missiles: they transport and deliver their cargo of biomolecules to the desired targets—pathogenic bacteria, human cells, or other microbes. They could thus serve as natural alternatives to chemical preservatives, while positively stimulating our immune system.

The objective of this thesis project is to produce, purify, and analyze these extracellular vesicles derived from food-borne microorganisms in order to test their ability to block the growth of major pathogens and interact with immune system cells without causing adverse effects. This work will be based on a comprehensive approach: from the selection of strains in the microbial collections of the SECALIM unit and the B-FHIT platform, to biological tests on human intestinal and immune cells in the laboratory.

But that's not all: by observing the molecular content of these EVs, the team will seek to identify specific “fingerprints,” or biological markers that distinguish effective EVs from others. This innovative and sophisticated approach will ultimately enable the selection of the best candidates for applications in agri-food or human health.

In short, this project combines microbiology, bioproduction, and immunology to investigate natural and sustainable solutions to the challenges of food health and food safety. Supported by the combined expertise of the SECALIM unit (expertise in the field of microbiological food safety and microbial interactions), the IECM (expertise in VE characterization), and the B-FHIT platform (expertise in VE bioproduction), this work aims to make a concrete contribution to the food of tomorrow, where nature inspires the most promising technologies