Adaptation and degradation of PFAS by the bacterium Pseudomonas putida

Per- and polyfluoroalkyl substances (PFASs) are a class of very diverse chemicals found in products of daily use, that are highly persistent and encountered everywhere in the environment. They accumulate/biomagnify within the natural food chain and show a relatively high toxicity including the alternative products developed after the ban of the legacy compounds. Therefore, the world is facing a situation of great concern all the more as the retreatment of contaminated soils, sediments and water is difficult and costly. One of the main challenges is because various PFASs have quite different physicochemical properties but are often encountered in mixture making it difficult to find a technology efficient to remove all of them. We propose to pave the way towards another approach for PFASs elimination, bioremediation that is known to be a good alternative to chemical or physical methods for removing toxics (self-sustainability, cheaper, working in milder conditions, and often with dissolved and sorbed contaminants). A few bacteria have been described to be able to partially modify/degrade some PFASs. However, except the aspect of PFAS transformation, no data are available concerning their adaptation to PFAS exposure. A few projects are focusing on finding enzymes implicated in the degradation per se but if we want to use bacterial cultures and not enzymes, many other parameters need to be taken into account to set up a performant strain and hence a performant process. Therefore, we propose to analyze in depth the response to several PFASs of the PFAS degrading strain Pseudomonas putida ATCC 17514 in term of degradation, adaptation to a potential toxicity and metabolism adjustment. The analyses will mainly rely on a proteomic approach that is a very powerful technique to analyze global responses without a priori, and has never been done to characterize PFASs toxicity or fluorinated compounds metabolism in bacteria. The ultimate goal after this bootstrap project will be to engineer or select a robust and efficient strain capable of biodegrading PFASs.

Chemical biology approaches to rare earth toxicology in Humans

Recent technological developments have expanded and intensified the use of lanthanides in domains as diverse as renewable energy, computing, and medicine. Increasing usage of these metals raises the question of their impact on the environment and human health. However, the potential toxicity of these metal ions, and its underlying molecular mechanisms, are still little known and rarely investigated in human cell models. The goal of the PhD will be to investigate the human cells response to exposure to Ln ions, and to systematically identify the proteins involved in this response, using a set of chemical and biological tools. In particular, we want to address the following questions: which protein networks are activated or deactivated following Ln exposure? Do Ln ions affect phosphorylation of proteins? Which proteins are directly interacting with Ln ions? will thus decipher what are the key biological interactors of lanthanides, their roles in living systems and the features that enable efficient binding to metals. We expect that our findings will give insights into the toxicology of those elements and inform environmental and occupational safety policies. On the longer term, new bio-inspired strategies for their extraction, recycling, decorporation and remediation will arise from the molecular understanding of metal-life interactions, enabling a well thought-out usage of these elements to support the environmental and numerical transitions.s