Phospholipids of Five Pseudomonad Archetypes for Different Toluene Degradation Pathways

Abstract

Liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) was used to determine intact phospholipid profiles for five reference pseudomonad strains harboring different (aerobic) toluene catabolic pathways: Pseudomonas putida mt-2, Pseudomonas putida F1, Burkholderia cepacia G4, Burkholderia pickettii PKO1, and Pseudomonas mendocina KR1. These five strains contained a predominant pool of phosphatidylethanolamines. Other phospholipids identified include phosphatidylglycerol, phosphatidylserine, phosphatidylmethylethanolamine, and phosphatidyldimethylethanolamine. There was a clear separation in phospholipid profiles that allows for the differentiation between the Pseudomonas and Burkholderia genera. Factor analysis of the phospholipid profiles showed that B. cepacia G4, P. putida mt-2, and B. pickettii PKO1 were clearly separated, while P. putida F1 and P. mendocina KR1 were clustered as a group. These results suggest that intact phospholipid profiling could be used to evaluate the relative abundance of specific degraders in bioreactors or in aquifer material. Nevertheless, the usefulness of this technique for taxonomic characterization of such complex samples remains to be demonstrated because of potential confounding effects of overlapping profiles and potential changes in phospholipid composition due to different growth conditions.