NERC/NSF-GEO: Constraining the source organism and function of bacteria membrane lipids to develop a robust terrestrial paleotemperature proxy

Reconstructing how land temperatures changed over geological time is critical for understanding Earth’s geologic past. So far, oceans have been the main source of ancient geological data, leaving the land’s history largely untold. This project will investigate a recently discovered, unique group of bacterial membrane lipids that are well preserved in the rock record and could function as molecular fossils that provide valuable information on past ecosystems. This work aims to improve understanding of Earth’s environmental history, train the future workforce, and contribute to fields such as microbiology, biogeochemistry, and cellular dynamics. Insights on how microorganisms adapt to changing environmental conditions could also have implications for biotechnology, bioengineering, and even the search for life on other planets. This project will explore the use of bacterial membrane lipids called branched glycerol monoalkyl glycerol tetraethers (brGMGTs) as geological proxies that can provide insight on past terrestrial environments. The study will (1) identify the bacteria that produce brGMGTs through heterologous gene expression, (2) develop a culture-based temperature calibration of brGMGT production, and (3) use computer simulations to determine the biophysical impacts of brGMGTs in membranes. These results will allow the development of a brGMGT paleothermometer that would be widely adopted as a robust terrestrial proxy. These advances could transform understanding of past terrestrial environments and open new research frontiers in microbial ecology, environmental chemistry, and microbial membrane dynamics. This award was made possible through the NSF/GEO-UKRI/NERC lead agency opportunity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.