Phospholipid compositional changes of five pseudomonad archetypes grown with and without toluene

Bacterial physiological responses to toluene exposure were investigated in five reference pseudomonad strains that express different toluene degradati on pathways: Pseudomonas putida mt-2, Pseudomonas putida F1, Burkholderia c epacia G4, Burkholderia pickettii PKO1, and Pseudomonas mendocina KR1. The intact phospholipids of these archetypes, grown with and without toluene, w ere characterized using liquid chromatography/electrospray ionization/mass spectrometry. All strains showed significant changes in phospholipid conten t and composition as an adaptive response to toluene exposure, as well as c onsiderable diversity in response mechanisms. For example, the phospholipid content of toluene-grown PKO1, F1, and KR1 were 10.9-34.7% of that found i n succinate-grown strains, while the phospholipid content of mt-2 and G4 in creased by 56% and 94%, respectively, when grown on toluene. In addition, P KO1, F1, and mt-2 responded to the presence of toluene by synthesizing more phosphatidylglycerol, whereas G4 and KR1 synthesized phospholipids with po lyunsaturated fatty acids (C18:2) on one or both of the sn-2 positions. The se changes in phospholipid composition and concentration probably reflect t he sensitivity and degree of tolerance of these strains to toluene, and sug gest that different mechanisms are utilized by dissimilar bacteria to maint ain optimal lipid ordering in the presence of such environmental pollutants .