Phospholipid Content of Pseudomonas aeruginosa PAO1 Is Modulated by the Growth Phase Rather Than the Immobilization State.

Abstract

Biofilms have significance in medical, industrial, and environmental settings, and can cause important damage. As biofilms are tolerant to various stresses, including antibiotics, it is necessary to better understand their formation. For this reason, we characterized the phospholipidome of Pseudomonas aeruginosa, an opportunistic pathogen involved in numerous infections, during the first steps of the biofilm development. By a liquid chromatography-tandem mass spectrometry time-course analysis over a 24-h period, we compared the phospholipid (PL) composition of immobilized (attached) and planktonic (unattached) P. aeruginosa PAO1 cells. Our results showed that the PL content of P. aeruginosa PAO1 was mainly modulated by the incubation time, thus related to bacterial growth but also, more modestly, by the immobilization state. We observed that relative amounts of PL varied over time with two main profiles and that these profiles are correlated to its fatty acid composition, including the degree of unsaturation. A statistical analysis revealed that the PL contents of both attached and unattached PAO1 cells were significantly different mainly after 3 and 6 h of incubation and that the amounts of two PL presented a statistical difference between attached and unattached cells all along the 24-h period: PtdEtn 16:0_18:1 and PtdEtn 18:1_18:1.