PROSTO MESTO ZA PODOKTORSKO IZOBRAŽEVANJE

Prosto mesto za podoktorsko izobraževanje

POSTDOCTORAL SUBJECT

TITLE: Role of microbial interactions in mercury methylation

ABSTRACT:
Mercury (Hg) is a persistent pollutant, highly volatile that can be converted into highly toxic methylmercury (MeHg). MeHg is a serious threat as it is a neurotoxic compound, which is bioaccumulated and bioamplified in food webs. Microorganisms play a central role in MeHg conversion, by controlling Hg methylation and MeHg degradation. However, little is known about the cellular, interspecific and environmental mechanisms favouring Hg transformations.
The role of microorganisms in biotic transformations of mercury species and their significance with respect to different metabolisms in the same microbial community are hardly known. The microorganisms in their environment interact with each other, for example, primary producers with nutrients recycling microorganisms (Fe, S, C compounds principally), and these interactions can affect the global mercury cycle. The current knowledge in Hg cycle originate from studies of few microorganism models. It is now important to advance these knowledge’s by relating Hg transformations, especially Hg methylation, to environmental relevant microorganisms. Indeed, few microorganisms are known to methylate mercury, although many more are suspected to perform this process but not cultivated yet. Notably, trophic transfers between primary producers and/or heterotrophic methylators are of interest to understand mercury methylation in natural ecosystems. In addition, previous studies have demonstrated the important role of thiol-compounds in mercury transformation, and therefore the transfer of thiols between microorganisms should also be deciphered.

Keywords: mercury speciation, microbial ecophysiology, autotrophs, heterotrophs, sulfate-reducing bacteria, iron reducing bacteria, anoxygenic phototrophs, fermentative, sulphide oxidizers, trophic transfer and thiols.

WORKING CONDITIONS

Laboratoire: Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Matériaux (IPREM UMR 5254, Pau) Site web: https://iprem.univ-pau.fr/fr/index.html

Post-doc Supervisors: Rémy Guyoneaud
The proposed post-doctoral position is part of the project ‘MesMic’ (Metals in Environmental Systems Microbiology) funded by E2S from 2018 to 2022. MesMic, selected as a ‘Hub E2S-UPPA’ (http://e2s-uppa.eu/en/index.html) is a collaborative and transdisciplinary project involving microbiology and analytical chemistry. The objective of the project is to unravel metal ion interactions with microbial ecosystems at the molecular, cellular and community levels. 6 PhD and 6 Post-Doctorates are funded by MesMic project.
Scientific team:
Molecular microbiologists: M. Goñi, B. Khalfaoui-Hassani, C. Gassie,
Microbial physiologists: R. Guyoneaud,
Geochemists and analytical chemists: D. Amouroux, Z. Pedrero, L. Rongo, L. Ouerdane, E. Tessier,
3 PhD students, and 1 post-doc.

Place: IPREM, Pau

Duration: 1 to 3 years

Start: Spring 2020 to summer 2020

Employer: Université de Pau et des Pays de l’Adour (UPPA)

HOST LABORATORY PROFILE

Microbiology, Physiology, Molecular Microbiology, Microbial Ecology
Analytical chemistry

MISSION – PRINCIPAL ACTIVITIES

1. The candidate will work with strains from different metabolic groups, including Desulfobulbus (sulfate reducer), Geobacter (iron reducer), Syntrophobacter (fermentative), and some autotrophs (to be determined). These bacteria are often associated in the environment and are involved in different reactions in mercury cycle. Co-cultures of two or more of these strains will be established in order to decipher the role of microbial interactions (carbon transfer, sulfur recycling, production of thiols, variations in environmental parameters). The genomes of selected strains are sequenced, and some of them can be used as models for genetic purposes.
2. The candidate will also work with natural samples known to efficiently methylate mercury. Indeed, metagenomic data show that many populations that could be involved in mercury methylation remain uncultivated. Therefore, high-throughput isolation approaches will be used in order to cultivate and isolate new bacterial or archaeal candidates involved in mercury methylation. Their representation in their natural community will be established through barcoding diversity analysis.
Candidate will perform physiological studies to understand the changes in cell growth, gene expression and mercury methylation and speciation. The post-doc will work with two PhD students, specialist on analytical chemistry and microbial physiology. The candidate should have skills in microbial physiology.

REQUIRED COMPETENCES

Microbial Ecology and Physiology, cultivation of microorganisms
Molecular Biology

SELECTION CRITERIA

Two steps selection process:
1st step:
- Evaluation of the applicants’ CV
- Candidates will be contacted by e-mail before January31st 2020
2nd step: (February 2020, date to be determined)
- Interview of the selected candidates (either at the IPREM or by videoconference)
- Candidates will have 5 min to present their CV, 5 min to present their PhD and 5 min to present their views on the post-doc subject
- Discussion with the candidates for at least 20 min
Criteria used during the selection of the candidates:
- The candidate's motivation, scientific maturity and curiosity.
- Candidate's knowledge on microbial ecophysiology and metabolism
- Candidate's publications
- English proficiency
- Candidate's ability to present his work
- Experimental proficiency

APPLICATION , DEADLINE

Application should be send by e-mail. The application should contain in one file:

• Cover letter detailing candidate's motivations
  
• CV
  
• Candidate's PhD abstract and publications
  
• At least two letters of recommendation
  
• Contact details (2 referees, including the PhD supervisor and the post-doc supervisor (if applicable))

DEADLINE: January 24th 2020

CONTACT

Name: Rémy Guyoneaud
e-mail: remy.guyoneaud@univ-pau.fr

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