The origins and fate of archaeal intact polar lipids in hydrothermally altered sediments of Cathedral Hill, Guaymas Basin, Gulf of California

Abstract

This study provides a survey of archaeal intact polar lipids (IPLs) and core lipids (CLs), focusing on archaeal lipids extracted from surface sediments within a push core transect that was collected at the Cathedral Hill hydrothermal vent complex in Guaymas Basin, Gulf of California. The main objectives of this study were to: 1) detect the subsurface microbial communities present, 2) determine the thermochemical stability of the lipids and, 3) evaluate if the thermochemical stability of these molecules influence lipid-based proxies used for the reconstruction of environmental change. In this study, a lipidome was detected providing evidence for the presence of archaeal communities that extend to sediment depths at ~145°C. These conditions are currently outside the known habitability of life. Evidence is provided that the archaeal communities adapt to the harsh conditions by modifying the core lipid structures of their cellular membranes. However, this adaptability appears to also impact the lipid-based proxies that are used to reconstruct present and past environmental conditions. These results suggest that an overprinting of original allochthonous signals is possible.