Recent Advances in Lipidomics of Extremophiles: A Review on Organic Biosignatures

Extreme environments on Earth are often studied as analog environments on other planetary bodies, since other planetary bodies in our solar system have extreme conditions for life as we know it. Extremophiles are commonly studied in astrobiology given that these microorganisms can survive in extreme conditions (e.g., pressure, temperature, pH). Omics aims to characterize and quantify biological molecules that regulate the structure, function, and dynamics of organisms; hence these methods can improve our understanding of their adaption strategies. The properties of the membranes of extremophiles, for example, which are amphiphilic molecules like lipids and fatty acids, play a key role in their adaptation to extreme conditions. Lipidomics of contemporary extremophiles offer a way to study the composition of their lipids exposed to a variety of stress conditions. Lipids are geostable biomolecules that can retain information about their biological origin for more than a billion years. Therefore, the ability of these molecular fossils to become preserved in extreme environments and assist in the reconstruction of early life on Earth indicate that they are likely to survive if preserved in extreme environments elsewhere. This review article highlights the importance of lipidomics in astrobiology and connects contemporary extremophilic lipids with the lipid fossils to outline approaches to detect extraterrestrial microbial life.