title: Liquid chromatography/mass spectrometry for the identification and quantification of rhamnolipids.
abstract: Rhamnolipids (RL) are surface-active glycolipids produced by Pseudomonas aeruginosa. They are always produced by this bacterium as a complex mixture of congeners, each composed of one or two rhamnose molecules linked to a dimer of 3-hydroxyfatty acids with a chain length of 8-12 carbons. Increasing interest for RL drives the need for efficient analytical methods to characterize these mixtures of molecules. High-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS) is a very precise and relatively high-throughput method for the identification of each congener and their quantification in bacterial cultures. Using (13)C-labeled RL as internal standards can further enhance the precision of the quantification. Collision-induced dissociation (CID) experiments by MS/MS is a powerful tool for the detection and identification of structural variations in RL produced by various Pseudomonas strains or by a specific strain under different culture conditions. CID even allows the discrimination between isomers with subtle structural variations, like Rha-C8-C10 and Rha-C10-C8, which are almost inseparable chromatographically. We are presenting here the detailed protocols for HPLC/MS and HPLC/MS/MS analysis of RL and their lipid precursors, the 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAA), directly in bacterial culture supernatants.
authors.affiliation: INRS-Institut Armand Frappier, Laval, QC, Canada, H7V 1B7.
authors.forename: Ahmad Mohammad
authors.initials: AM
authors.lastname: Abdel-Mawgoud
authors.forename: François
authors.initials: F
authors.lastname: Lépine
authors.forename: Eric
authors.initials: E
authors.lastname: Déziel
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid / Q000379:methods*; D006017:Glycolipids / Q000032:analysis* / Q000737:chemistry; D057230:Limit of Detection; D013058:Mass Spectrometry / Q000379:methods*; D011550:Pseudomonas aeruginosa / Q000378:metabolism
chemical_list: D006017:Glycolipids; C418382:rhamnolipid