title: Characterization by electrospray ionization and tandem mass spectrometry of rhamnolipids produced by two Pseudomonas aeruginosa strains isolated from Brazilian crude oil.
abstract: In this work, biosurfactants produced by two Pseudomonas aeruginosa strains isolated from Brazilian crude oils were identified by proton nuclear magnetic resonance ((1)H NMR) and further characterized by mass spectrometry (MS) coupled with electrospray ionization (ESI) and tandem mass spectrometry (MS/MS) analysis in positive mode and their surface activities evaluated. Mono-rhamnolipids and di-rhamnolipids were identified for both isolates, but the most abundant were found to be mono-rhamnolipids. The similarity of rhamnolipids produced by the two strains was in good agreement with their surface activities. Both biosurfactants exhibited similar aqueous solution surface tensions, high emulsification indexes and critical  micelle concentration values. The results obtained show that ESI-MS and MS/MS analysis alone provide a fast  and highly specific characterization of biosurfactants produced by microbial strains.
authors.affiliation: CICECO-Chemistry Department, University of Aveiro, Portugal.
authors.forename: Jorge F B
authors.initials: JF
authors.lastname: Pereira
authors.forename: Eduardo J
authors.initials: EJ
authors.lastname: Gudiña
authors.forename: M Luísa
authors.initials: ML
authors.lastname: Dória
authors.forename: M Rosário
authors.initials: MR
authors.lastname: Domingues
authors.forename: Lígia R
authors.initials: LR
authors.lastname: Rodrigues
authors.forename: José A
authors.initials: JA
authors.lastname: Teoxeira
authors.forename: João A P
authors.initials: JA
authors.lastname: Coutinho
mesh_terms: D006017:Glycolipids / Q000032:analysis* / Q000737:chemistry*; D010578:Petroleum / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000145:classification* / Q000378:metabolism*; D013045:Species Specificity; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D006017:Glycolipids; D010578:Petroleum; C418382:rhamnolipid