Maxime Bridoux, Commissariat à l’Energie Atomique et aux Energies Alternatives, Département Analyse et Surveillance de l’Environnement (DASE) donnera un séminaire le 23 avril 2024 à 11h00 – Amphithéâtre Oceanomed, sur .le sujet suivant : Weighting molecules with the precision of an electron to understand the biogeochemistry of organic matter on a global scale.

Résumé

Molecular biogeochemistry blends concepts from geology, chemistry, and biology to study the cycling of biological elements (C, N, P, S, …) throughout various Earth systems. While targeted molecular biogeochemistry provide information on the regulation of individual processes and typically involve isolating and purifying individual biomarkers to analyze their stable or radioactive isotopes (d13C, D14C, d15N …), non-targeted approaches have recently emerged as new, powerful techniques with a wealth of applications. Indeed, non-targeted workflows are now able to characterize full molecular and isomeric complexity of organic and organometallic mixtures and track their turnover across environmental gradients in a few hundred of microliters of sample! At this stage, organic geochemistry meets environmental metabolomic.

With its unmatched mass resolving power (Rs> 1 000 000 @ m/z 400) and mass accuracy (<1 ppm), Fourier transform mass spectrometry (FTMS; i.e. FT-ICR MS, Orbitrap Lumos 1M MS) is rapidly evolving into a reference analytical tool for environmental chemists, and biogeochemists. FTMS opens the door to nontargeted, molecular-level identification of organic and organometallic compounds and the elucidation of their abiotic and biological transformations in virtually all environmental matrices from atmospheric, aquatic (freshwater and marine), terrestrial (soils and sediment archives) and extraterrestrial compartments. Finally, it also enables the measurement of accurate isotopic ratios of individual compounds within complex mixtures and to assess previously inaccessible isotopologues.

This seminar will present the development of various targeted and non-targeted molecular biogeochemical workflows in my lab, applied to characterize the source of various pools of organic matter in terrestrial, atmospheric and marine environments and their biotic / abiotic biogeochemical transformations. We will show that, combined with the recent developments in advanced bioinformatic methods of visual representation of complex mass spectral features and the implementation of machine learning tools, non-targeted (FTMS) analysis allows the discovery of information hidden in biogeochemical data, improving our comprehension of the Earth system.