Description:

Topic: Mercury methylation and transformations by sulfate-reducing bacteria

Abstract:

Mercury (Hg) is a concerning pollutant on Earth, particularly because it converts into methylmercury (MeHg), a strong human neurotoxin. MeHg is mainly produced in the environment by sulfate-reducing bacteria (SRB) and is then biomagnified and bioaccumulated in the aquatic food web, thus resulting in health issues for consumers at the top of the food web. Untangling the biotransformation processes of Hg by these microorganisms is thus a key to grasping the release of MeHg in ecosystems. 

To clarify the mechanisms occurring at the microbial cell level, we focus on the model SRB strain Pseudodesulfovibrio hydrargyri BerOc1 originated from a Mediterranean lagoon that is able to methylate and demethylate mercury. Our approach combines High Energy Resolution Fluorescence Detected-X-ray Absorption Near Edge Structure spectroscopy and nano-X ray fluorescence imaging to identify Hg species and Hg cellular localization. In this presentation, I will show some of our recent results and the multi-modal imaging approach that we are carrying out.

Biography:

Marie-Pierre Isaure is an Associate Professor in the IPREM Institute at Pau University in France (Université de Pau et des Pays de l’Adour). She received her PhD in Geochemistry from Grenoble University in 2001, and was a post-doc at Ecole Normale Supérieure in Paris, CEA-Grenoble and Grenoble University. She develops a multi-scaled approach going from the field and culture analysis to the microscopic and atomic level, with a particular interest in chemical imaging and X-ray Absorption Spectroscopy. She has been granted a 6 month Fulbright fellowship to conduct research at Advanced Photon Source at Argonne.