Substantial contribution of in-situ produced bacterial sphingolipids to the sedimentary lipidome

Abstract: The sedimentary lipid pool comprises a myriad of components with some specific biomarkers used in paleoclimatic and geobiological reconstructions. However, a comprehensive view of the sedimentary lipidome is lacking. Here we conduct an untargeted analysis of the Black Sea sedimentary lipidome using high resolution mass spectrometry. Besides commonly reported phytoplankton-derived fossil lipids originate from oxic surface water, a diverse and abundant set of sphingolipids, accounting for ~20% of the lipidome, was discovered. These sphingolipids are produced in-situ by sedimentary anaerobic bacteria, likely in place of phospholipids due to the deficiency of phosphate in anoxic sediments. Our results suggest that while phytoplankton-derived lipids contribute 50–60% of the sedimentary lipidome, the importance of bacterial lipids, particularly in-situ produced sphingolipids, has been overlooked.

Source data:

Data 1. Information of 4,194 lipid species classified from the molecular network, including their ID, parent mass, retention time, adduct, peak intensity and etc. 

Data 2. Information of tantatively identified 928 lipid species from the molecular network, including their ID, parent mass, retention time, adduct, abundance and etc. Lipid abundance were expressed as ng L⁻¹ for SPM samples from the water column and ng g⁻¹ for sediment samples. The proportion of lipid species identified was then used for further analysis.

Data 3. Lipid abundance transformed to ng g⁻¹ TOC in sediment samples