Exploring the lipidomes of shallow-water and deep-sea hydrothermal systems

This dissertation focuses on the microbial ecology in hydrothermal systems, more specifically on the lipidome and encoded lipid structure-functions of microbial membranes. Shallow-water hydrothermal sediments off the coast of Milos and Dominica were investigated and analyzed for microbial membrane adaptations to different geochemical parameters. Information encoded in the assemblages of polar lipids revealed an increase in cell membrane fluidity in concert with reduced permeability as an adaptive response of both archaea and bacteria to e.g. elevated sediment temperatures. The final chapter of this thesis shows the carbon transfer from chemosynthetic bacteria to higher trophic levels in the fluids from diffuse-flow vents of the East Pacific Rise. Furthermore, the combined lipidomic approach with stable carbon isotopic analysis of lipids allowed the prediction that eukaryotes rather than bacteria are the dominant source of lipids in the investigated samples.