Our group specializes in the application of interdisciplinary approaches – borrowing methods from the fields of biology, geology, and chemistry – to solve complex environmental questions related to biogeochemical cycling.
The Lichen Microbiome
Lichens are a stable symbiosis between a fungus and a photosynthetic partner, which can be either an alga or a cyanobacterium. Only recently has it been recognized that a third symbiotic partner—bacteria—colonizes both the surface and interior of lichens, but their role within this association remains largely unknown. Much like the human microbiome contributes to immune defense and nutrition, the lichen microbiome may play a role in lichen ecophysiology and fitness. These bacteria mostly belong to the Alphaproteobacteria and have been found to be lichen species-specific and significantly different from microbial communities on surrounding substrates. We therefore apply microbiological techniques to investigate the role of the lichen microbiome in adaptation to environmental conditions, enabling this organism to colonize even the most extreme environments on Earth.
Surprising microbial metabolisms
From the presence of aerobic methanotrophic bacteria in anoxic sediments to microbial iron reduction in oxic waters, more and more exceptions to the dogma of a thermodynamic redox tower are being discovered. We use tools such as microfluidics, metagenomics and -transcriptomics, and in situ activity measurements to prove that these unexpected microbial processes are active and to disentangle how they are possible. Ongoing projects involve microbial iron, sulfur, and methane cycling.
Open Master’s projects:
Co-evolution de la qualité de l’air et les lichens corticoles en région Genevoise
Les lichens épiphytes ont été utilisés comme bioindicateurs pour réaliser une étude de la pollution atmosphérique dans le canton de Genève en 1986 et en 1996. On a pu constater des changements dans la répartition des espèces lichéniques, qui correspondent à des modifications de la qualité de l’air. Bien que des techniques avancés de monitoring de la qualité de l’air indiquent une nette amélioration de la qualité de l’air depuis les années ‘90, le rétablissement des communautés de lichens dans la région genvoise reste inconnu. Des relevés de biodiversité lichénique seront effectués aux memes coordonnées que l’étude de Fiore-Donno (1997) pour évaluer l’évolution des communautés de lichens dans région genvoise. Ces donnés seront mis en contexte avec les donnés de qualité de l’air disponible pour sept stations de mesures dans le canton.
Connaissances nécessaire et méthode(s) de travail: Ce travail requiert une maitrise des techniques d’identification des lichens ou une volonté d’apprendre. Le module lichens I à l’HEPIA est recommandé. Bonne connaissance de la langue française.
Open Bachelor’s projects: please inquire directly for any customized projects applying sediment geochemistry, water quality, or microbiology…
- Comparative assessment of N2 fixation and greenhouse gas production by legume crops, invasive green alder, and natural N2 alder stands.
- Aulnus viridis is perceived negatively as it is rapidly recolonizing abandoned alpine pastures and contributes to N2O production, but this has not been contextualized in relation to other N2-fixing plants.
- Literature review of published data on N2O production by different plants with symbiotic N-fixing bacteria
- Understanding controls on water chemistry in la gouille de Conche (Val d’Illiez)
- High levels of Fe and Mn alongside other metals have been reported by the Service de l’Environnement du Valais. The objective of this project is to determine the source of these metals by analysing sediments, lake and river water, and soils in the catchment area.
- Principal methods used: microwave digestion, ICP-OES
- Monitoring microbiological water quality below alpine tourist infrastructures lacking water treatment systems
- It is not known how far wastewater from mountain huts contaminates surface water runoff before being diluted out. Wastewater from the Cabane Valsorey empties directly into the Torrent de Valsorey and is progressively diluted by other rivers before merging with the Dranse.
- The project will involve collecting water samples at different points along the river and performing bacterial analyses in the laboratory