Master 2 Internship Offer on the stability and preservation of cell envelopes under UV (Paris)

6-month Master 2 internship focused on the stability and preservation of microbial cell envelopes under UV-exposure, both on Earth and in space, in preparation for the Exocube experiment on the International Space Station (ISS).

About the role

The preservation of microbial biosignatures in extreme conditions is crucial to distinguish traces of primitive life from abiotic organic signatures. This project will evaluate the structural stability of halophilic archaea cell envelopes under high-UV conditions, including simulations of Low Earth Orbit (LEO) environments for the Exocube experiment. The Exocube space exposure platform, developed by the European Space Agency, aims to study the biological and photochemical stability of life’s building blocks and cell surface components to aid planetary exploration and life-detection missions.

Responsibilities

• Compare the stability of cell envelope extracts and whole cells (living and dead) of halophilic archaea, both within and outside halite crystals, under full UV irradiation (200-400nm) using a solar simulator.
• Test protocols for in-flight analyses (fluorescence/FT-IR spectroscopies) and post-flight analyses (atomic force/electron microscopies) of cell envelope integrity.
• Collaborate with the Exocube principal investigator, Dr. Andreas Elsaesser at Freie Universität Berlin.

Requirements

• Background in microbiology and/or biochemistry.
• Strong interest in exobiology.

Research Context

Microbial cell envelopes (cell wall + lipid membrane) have strong potential to preserve biosignatures over geological timescales. Hypersaline environments, such as those containing halite (NaCl), challenge the stability of key microbial biomolecules like proteins and lipids but can also protect and preserve microbial structures. Halophilic archaea, such as Halobacterium salinarum, exhibit resistance to desiccation, high vacuum, UV-C, and gamma irradiation due to specific molecular adaptations. The cell envelope of these archaea consists of a simple yet robust structure: a cell membrane of ether-linked lipids with isoprenoid chains, surrounded by a proteinaceous surface layer (S-layer).

This project will contribute to understanding how cell envelopes withstand UV exposure, with implications for interpreting findings from planetary exploration missions.

Supervisor: Dr. Adrienne Kish
Lab: UMR 7245 MCAM (Molecules of Communication and Adaptation of Microorganisms), Muséum national d’Histoire naturelle, 63 rue Buffon, 75005 Paris