Fig. 1
A Molecular network of the major lipid classes in the Sulfurimonas species (Ca. S. marisnigri SoZ1, Ca. S. baltica GD2 and S. gotlandica GD1T) using \({{{{{{{\mathrm{NO}}}}}}}}_3^ -\) or MnO2 as electron acceptors. Nodes represent MS/MS spectra of ion components (lipids), which are connected based on spectral similarity (cosine > 0.6). Nodes are filled with pie charts which contain four different colors representing the fractional abundance of the lipid (based on peak intensity) among three Sulfurimonas species with two different treatments. The size of each pie charts represents for the summed intensity of the ion component in all the species using various electron acceptors. The aim of this figure is not to compare the abundance of lipids among different Sulfurimonas species, rather than that it provides information on whether specific Sulfurimonas spp. under certain conditions have the ability to synthesize specific lipids. The spatial orientation of the nodes in the MS/MS network is randomly generated by Cytoscape [58, 59] and does not relate to relationships between the subnetworks. Lipid classes (clusters) with annotation are either tentatively identified in this study or have been annotated from the GNPS library (see the method for details). B Major lipid class composition (based on peak intensity). DAG diacylglycerol, AEG acyletherglycerol, LCF long chain fatty acids, PE phosphatidylethanolamine, PG phosphatidylglycerol. There are also three unknown lipid classes, the structure of unknown lipid 1 will be discussed in Fig. 3. The other two lipid classes are lipids with polar headgroups that we could not identify based on their mass spectra. However, their mass spectra indicate that they comprise a DAG core (Fig. S1).
