Lipidomic Analysis Reveals Differences in Bacteroides Species Driven Largely by Plasmalogens, Glycerophosphoinositols and Certain Sphingolipids

There has been increasing interest in bacterial lipids in recent years due, in part, to their emerging role as molecular signalling molecules. Bacteroides thetaiotaomicron is an important member of the mammalian gut microbiota that has been shown to produce sphingolipids (SP) that pass through the gut epithelial barrier to impact host SP metabolism and signal into host inflammation pathways. B. thetaiotaomicron also produces a novel family of N-acyl amines (called glycine lipids) that are potent ligands of host Toll-like receptor 2 (TLR2). Here, we specifically examine the lipid signatures of four species of gut-associated Bacteroides. In total we identify 170 different lipids, and we report that the range and diversity of Bacteroides lipids is species specific. Multivariate analysis reveals that the differences in the lipid signatures are largely driven by the presence and absence of plasmalogens, glycerophosphoinositols and certain SP. Moreover, we show that, in B. thetaiotaomicron, mutations altering either SP or glycine lipid biosynthesis result in significant changes in the levels of other lipids, suggesting the existence of a compensatory mechanisms required to maintain the functionality of the bacterial membrane.

Automated summary

There has been increasing interest in bacterial lipids, particularly their role as molecular signalling molecules. Bacteroides thetaiotaomicron, an important member of gut microbiota, produces sphingolipids and glycine lipids that impact host metabolism and inflammation pathways. This study examined the lipid signatures of four gut-associated Bacteroides species, identifying 170 different lipids and showing species-specific differences. Mutations affecting lipid biosynthesis in B. thetaiotaomicron result in significant changes in other lipids, suggesting the presence of compensatory mechanisms for maintaining bacterial membrane functionality.