PG was found to be the predominant phospholipid in bacteria of the genus Bacillus and its phylogenetic relatives . Shah et al. identified 15:0/15:0-PG with m/z 693.4712 in the thermotolerant Geobacillus sp. strain GWE1 as one of the main phospholipids. Taking into account the published data and the results obtained in this study, we confirm that PG is the main phospholipid in the seven strains of bacteria and therefore was selected for further analysis. In addition, other homologs (molecular species) were identified for all strains.