Abstract
Microbialites are composed of a complex community of microbes whose net metabolic activity results in the deposition of carbonate rock. Modern microbialite structures actively grow in a variety of environments and are similar to the oldest preserved form of life on Earth. This research used lipid biomarkers to study the microbial composition of microbialites from a freshwater meromictic lake (Fayetteville Green Lake, NY) and a hypersaline shallow lake (Great Salt Lake, UT). Lipid biomarkers are useful for tracking similarities and differences in the autotrophic and heterotrophic community with variable growth conditions. This work focused on the hopanoid biomarkers, bacterial cellular membrane components preserved in ancient microbial carbonates. Hopanoid biomarkers including diploptene, hop-21-ene, diplopterol, tetrahymanol, bacteriohopanetetrol, and 2-methyl forms were present in microbialite samples, indicating similarities in microbial communities. The microbialites in New York and Utah are valuable for their broad applicability to studying past microbial life.