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Phd position H/F in microbial ecology and biogeochemistry to characterize cryosphere sugar transport and metabolism

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : mardi 12 juillet 2022

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General information

Reference : UMR5204-CHRPIO-001
Workplace : LE BOURGET DU LAC
Date of publication : Tuesday, June 21, 2022
Scientific Responsible name : Christine Piot et Catherine Larose
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

The main objective of this thesis is to determine whether snowpacks are able to modify the chemical signatures of S/SA/AS, their atmospheric inputs and potential transformations once deposited need to be characterized in relation to the microorganisms capable of metabolizing/producing S/SA/AS. This is critical for evaluating their suitability as tracers in ice archives. This will be addressed with combined field and laboratory studies at two alpine sites (Col du Lautaret and Col du Dôme), sampled in the winter of year 1, aiming to establish the fraction of S/SA/AS inputs by snow deposits (dry and wet), their evolution during winter both in terms of concentration and chemical fingerprints, and potential biological transformations, and finally, to determine what fractions are transferred to other compartments (ice or meltwater). A total of 5 campaigns will be carried out at different times of the year at Col du Lautaret, where existing instrumentation for atmospheric and wet deposits will be used. Parallel samples will be collected for microbial and S/SA/AS analysis. Field based studies will provide insight on potential biogeochemical transformations and the organisms involved, but cannot be used to isolate purely microbially-derived S/SA/AS snowpack signatures due to the complexity of the system and high number of confounding factors, such as continual atmospheric inputs. In order to address this and provide both a microbially-mediated snow S/SA/AS signature and a mechanistic understanding of how these transformations occur, a series of snow microcosm studies will be carried out. The main objectives are to (i) identify the organisms, genes and pathways involved in snowpack S/SA/AS metabolism, (ii) compare these with field studies, and (iii) provide a laboratory-validated microbial S/SA/AS signature for snow.

Work Context

This PhD will be carried out within the framework of the ABS project (Atmospheric Biogenic Sugars) which has obtained financial funding from the ANR and started in the spring of 2022. The ABS project and this PhD allow the establishment of a collaboration between three CNRS UMRs: the Institute of Environmental Geosciences in Grenoble (CNRS/IRD/Grenoble-INP/UGA), the Ampère laboratory in Lyon (CNRS/ECL/INSA/UCBL) and EDYTEM in Chambéry (CNRS/USMB). The majority of the experimental work will be carried out at the Ampère Laboratory and at EDYTEM.

Additional Information

We are looking for a highly motivated candidate with a master degree in microbiology or biogeochemistry, and a background in environmental science. A first experience working at the chemical/biology interface would be a plus. The candidate must be able to integrate into teams of different cultures, have a strong taste for experimentation, be autonomous and know how to take initiatives. Laboratory skills in DNA extraction, qPCR, sequencing library preparation and data analysis using R would be an advantage.

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