4. Cell to cell bacterial communication / Quorum sensing & Quorum quenching
The oceans cover more than 70% of Earth surface, regulate its climate and atmosphere, and sustain living and non-living resources. With about 5×105 cells per milliliter marine prokaryotes are fundamental to the biogeochemical cycles that shape our planetary atmosphere and environment, by cycling nutrients, and ultimately influencing climate on a global scale. These last two decades, microbial ecologists have been examined the diversity of bacteria in the oceans, and the abiotic parameters shaping these communities have been extensively studied. However, biotic interactions within these populations remain poorly explored in the environment, and in particular quorum-sensing based interactions, implying cell-to-cell communications through the diffusion of autoinducers (bacterial “hormones”, AI). This is particularly surprising since a very large number of studies have characterized these molecules and their effects on bacterial models isolated in culture, in well-controlled laboratory conditions. In contrast, the diversity, the abundance, the expression and the ecological roles of these AI remain largely unexplored in the environment. The study of these mechanisms in the marine environment pave the way to fundamental discoveries, but also to much more biotechnologically oriented work (like application derived from "quorum quenching" to control bacterial growth, biofilms).
Our current project ("Emergence UPMC") aims to characterize the diversity and the role of the most important AI producing bacteria in the marine environment, as well as the chemical diversity of these molecules.