oa Unravelling the Biological Sources and Biosynthetic Mechanisms of Novel Bacteriohopanepolyol Biomarkers

Bacteriohopanepolyols (BHPs) are special lipid components found in the cell membranes of diverse bacterial phyla and are ubiquitously distributed across a wide range of environments. Among these, nucleoside (Nu)-BHPs are characterized by adenosyl or inosyl head groups and are predominantly identified in terrigenous and lacustrine settings, serving as a biomarker to estimate soil inputs to marine environments. Recently, Nu-BHPs with various modifications on the nucleoside head group, are widely found in soils and lakes, showing significant promise for developing paleoenvironmental proxies. However, uncertainties remain regarding the biological sources and biosynthesis of these novel Nu-BHP derivatives, as well as the physiological mechanisms underlying their responses to environmental variations. In this study, we investigate the BHP lipidomic profiles in the cultures of four bacterial species that produce diverse Nu-BHPs under various temperature and pH conditions, and will identify candidate genes responsible for the modification on the head group to unravel the biosynthetic pathway and physiological adaption of these novel Nu-BHPs. The findings of this study will provide a physiological basis for the development and application of molecular proxies based on novel Nu-BHP biomarkers indicating paleoenvironmental changes.