Microorganisms catalyze processes which shape the chemistry of the biosphere, drive global element cycles, and ultimately influence the composition of Earthâ s surface and interior on geological timescales. Microbial lipids provide crucial information about the distribution, activity, and adaptation of microbial communities in both modern and ancient environments. In this thesis, advanced chromatographic methods were developed that have significantly expanded the analytical window for microbial lipidomics in complex environmental sample matrices and have paved the way for the discovery of novel microbial biomarkers. Application of the novel protocols to samples from microbial cultures, the hypersaline Discovery Basin and the stratified water column and sediments of the Black Sea revealed an exceptional diversity of lipids. The combination of respiratory quinone and core and intact polar lipid analysis provided detailed information about microbial community composition and biogeochemical processes the microbes are mediating
