Master 2 internship: Molecular mechanisms of mercury methylation: France

1. Description of the project
Mercury (Hg) is a persistent pollutant, highly volatile and can be converted to the highly toxic methylmercury (MeHg). MeHg is a serious threat as it is a neurotoxic compound, which is bioaccumulated and bioamplified in food webs. In aquatic ecosystems, the methylation of Hg(II) to MeHg is mostly associated with the activity of anaerobes, mainly sulfate-reducing bacteria (SRB). While the genetic basis of Hg methylation seems determined, the mechanisms of Hg uptake into the cells (whether passive or active) are completely unknown. Interestingly, addition of metals like zinc (Zn(II)), copper (Cu(II)) or cadmium (Cd(II)) affect Hg methylation. These findings suggest that Hg uptake is a competition event between Hg and other divalent metals that rely on membrane bound protein transporter(s).

The proposed work aims at understanding the molecular basis of Hg biotransformation and trafficking in the well-characterized Hg methylator SRB Pseudodesulfovibrio hydrargyri BerOc1. The main objective is to discover new components affecting Hg methylation and Hg trafficking via divalent metals, especially Zn, Cd, and Cu, known to affect Hg methylation. To reach this objective, the master student will start by assessing physiologically the toxicity of Hg combined with the interfering metals in growing cells. The MeHg produced will be then measured using MeHg biosensor and GC-ICP-MS. These measurements will determine the ratio of Hg/Zn, Hg/Cd, Hg/Cu, and Hg/metals (cocktail of Zn, Cd, and Cu) that inhibit or activate Hg methylation. The work of the master student is expected to set the stage for a global proteome analysis of cells grown at the conditions where the MeHg production shows significant changes.

2. Working place and conditions
Our team is part of the IPREM Institute (Institut des Sciences Analytiques et de Physico-chimie pour l’Environnement et les Matériaux, CNRS, UMR 5254, Pau) and the STEE college at the University of Pau et des pays de l’Adour located South West of France.
The STEE college offers 6 months fellowship (550 Euro/month) to the successful candidate.

3. Candidate skills and expertise
The master 2 student should have solid background in microbiology and knowledge in physiology of anaerobes.

4. Deadline and how to apply
The interested candidates should send their application (in French or English) for a starting date on early 2020. The application should include all of the four following documents as a single PDF file by email to Bahia Khalfaoui Hassani (
1. Cover letter
2. Curriculum vitae
3. Brief summary of previous lab experience (1 page max)
4. Names and contact information for references or/and reference letters.

5. Suggested readings

1. Schaefer, Jeffra K., Aleksandra Szczuka, and François M. M. Morel. 2014. Environmental Science & Technology 48: 3007–3013. doi:10.1021/es405215v.
2. Lu, X., Johs, A., Zhao, L., Wang, L., Pierce, E.M., Gu, B., 2018. Environ. Sci. Technol. Lett. 5, 372–376
3. Goñi-Urriza, M, Y. Corsellis, L. Lanceleur, E. Tessier, J. Gury, M. Monperrus, and R. Guyoneaud. 2015. Environmental Science and Pollution Research 22: 13764–13771. doi:10.1007/s11356-015-4273-5.
4. Pedrero, Zoyne, Romain Bridou, Sandra Mounicou, Remy Guyoneaud, Mathilde Monperrus, and David Amouroux. 2012. Environmental Science & Technology 46: 11744–11751. doi:10.1021/es302412q.

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