Abstract
Porphyromonas gingivalis displays interesting phospholipid analogue profiles, which can vary between strains from different animal species. The purpose of this study was to compare human strains, isolated in different parts of the world, with respect to their phospholipid profiles. In all, 24 isolates from three continents were cultured and their lipids were extracted with chloroform-methanol and characterized by fast atom bombardment mass spectrometry (FAB-MS) in negative ion mode. Both lower mass (carboxylate) and higher mass (phospholipid analogue) anions were measured in each mass spectrum. Calculation of Pearson correlation coefficients for each strain pair was then followed by average linkage cluster analysis. The major lower mass anion observed for all strains analysed in this study was of mass-to-charge (m/z) 241, which is consistent with previous FAB-MS studies on P. gingivalis. The major phospholipid analogue anion observed for isolates from Manchester, UK, was m/z 960 which is an unknown phospholipid. Other major peaks were of m/z 662 and 663, which may be identified respectively as PE (30:0) and PG (28:1) with contributions from the first isotope of PE (30:0). It was observed that isolates from the same geographical location displayed similar phospholipid profiles. It is concluded that phospholipid profiles of human P. gingivalis isolates are diverse and that there can be differences between P. gingivalis isolates obtained from different geographical locations.