Search for: All records

Abstract Glycerol dialkyl glycerol tetraethers (GDGTs) are a group of membrane spanning lipids produced by both Archaea and Bacteria. Branched GDGTs (brGDGTs) are a class of these tetraether lipids known to be produced by certain bacteria and are commonly found in terrestrial environments. Due to their environmental ubiquity, high preservation potential, and role in membrane adaptation, brGDGTs form the basis of many widely employed paleoenvironmental proxies. The tetramethylated brGDGT Ia is the most commonly reported branched tetraether in culturedAcidobacteriaand is a key component of brGDGT‐based temperature indices. Herein, we report the first total synthesis of brGDGT Ia, thereby elucidating the relative configuration of the methyl branches as syn. We further demonstrate that VCD spectroscopy is a suitable tool to determine the absolute configuration of these cryptochiral compounds, a method waiting to be applied to the natural lipid, but currently hampered by its limited availability. 

Sphingolipids have long been of interest to the scientific community for their roles in eukaryotic cell structuring and disease pathology. Less is known about the occurrence and function of these diverse compounds in the bacterial domain of life, with most studies on bacterial sphingolipids focused on eukaryotic disease research and host-pathogen or host-symbiont interactions. Thus, bacterial contributions to environmental sphingolipid pools are poorly understood and the function of these lipids outside of pathogenicity remains largely unexplored. This report marks the first instance of sphingolipid production in a member of the phylum Acidobacteria, a globally ubiquitous phylum of soil bacteria. The occurrence of core- and intact-ceramides is reported for the AcidobacteriumSolibacter usitatusunder various environmentally relevant conditions. Shifts in the production of ceramides across temperature, pH, and oxygen gradients in this organism suggest that these compounds play a role in the physiological adaptation to environmental fluctuations. Additionally, the genetic basis of bacterial ceramide biosynthesis in this species is assessed and used to explore the potential for ceramide biosynthesis across the bacterial domain of life. The extent of the biosynthetic potential for Acidobacteria to produce ceramides coupled to the abundance of their genes in soil metagenomes suggests that soil sphingolipids should not be solely attributed to eukaryotic production.