Supported projects

Understanding the interactions between organisms and the environments in which they live is now essential for predicting and reducing the effects of environmental changes occurring on a global scale. By modifying the lipid composition of their membrane in response to prevailing environmental conditions, organisms will ensure the optimal state of the cell membrane. This natural mechanism of adaptation to variations in environmental conditions is particularly useful for understanding current biogeochemical processes and the impact of climate change on them. Glycerol dialkyl glycerol tetraethers (GDGTs), membrane lipids present in the membrane of archaea and certain bacteria, have been the subject of growing interest in recent years, as they constitute the only microbial markers currently applicable to paleoclimate reconstructions in both terrestrial and aquatic environments. The bacterial sources of these compounds, although present in all natural environments, remain largely unknown. This training period will aim to (i) identify the bacteria that are sources of GDGTs in the natural environment and (ii) to precisely investigate the adaptive mechanism of these microorganisms in response to temperature variations. To do this, we will use a library of Gram-negative bacterial strains isolated from soils and lakes. These strains will be screened to identify those whose membrane contains GDGTs. These bacteria will then be cultivated under controlled conditions, with varying temperatures. This mechanistic approach carried out at the microbial level will contribute to a better understanding of environmental markers based on bacterial tetraethers and should allow for more precise interpretation of (paleo)environmental data obtained after analysis of these compounds in natural samples.