title: MALDI-TOF mass spectrometry as a tool for differentiation of Bradyrhizobium species: application to the identification of Lupinus nodulating strains.
abstract: Genus Bradyrhizobium includes slow growing bacteria able to nodulate different legumes as well as species isolated from plant tumours. The slow growth presented by the members of this genus and the phylogenetic closeness of most of its species difficults their identification. In the present work we applied for the first time Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) to the analysis of Bradyrhizobium species after the extension of MALDI Biotyper 2.0 database with the currently valid species of this genus. With this methodology it was possible to identify strains belonging to phylogenetically closely related species of genus Bradyrhizobium allowing the discrimination among species with rrs gene identities higher than 99%. The application of MALDI-TOF MS to strains isolated from nodules of different Lupinus species in diverse geographical locations allowed their correct identification when comparing with the results of rrs gene and ITS analyses. The nodulation of Lupinus gredensis, an endemic species of the west of Spain, by B. canariense supports the European origin of this species.
authors.affiliation: Unidad de Investigación, Hospital Universitario de Salamanca, Spain; Instituto de Investigación Biomédica, Salamanca, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Sánchez-Juanes
authors.forename: Laura
authors.initials: L
authors.lastname: Ferreira
authors.forename: Pablo
authors.initials: P
authors.lastname: Alonso de la Vega
authors.forename: Angel
authors.initials: A
authors.lastname: Valverde
authors.forename: Milagros León
authors.initials: ML
authors.lastname: Barrios
authors.forename: Raúl
authors.initials: R
authors.lastname: Rivas
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Mateos
authors.forename: Eustoquio
authors.initials: E
authors.lastname: Martínez-Molina
authors.forename: José Manuel
authors.initials: JM
authors.lastname: González-Buitrago
authors.forename: Martha E
authors.initials: ME
authors.lastname: Trujillo
authors.forename: Encarna
authors.initials: E
authors.lastname: Velázquez
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D020369:Bradyrhizobium / Q000737:chemistry* / Q000145:classification* / Q000302:isolation & purification; D016000:Cluster Analysis; D031297:Lupinus / Q000382:microbiology*; D010802:Phylogeny; D053204:Root Nodules, Plant / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013030:Spain; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
keywords: Bradyrhizobium; Identification; Lupinus; MALDI-TOF MS; Rhizobia