title: Multilocus sequence-based analysis delineates a clonal population of Agrobacterium (Rhizobium) radiobacter (Agrobacterium tumefaciens) of human origin.
abstract: The genus Agrobacterium includes plant-associated bacteria and opportunistic human pathogens. Taxonomy and nomenclature within the genus remain controversial. In particular, isolates of human origin were all affiliated with the species Agrobacterium (Rhizobium) radiobacter, while phytopathogenic strains were designated under the synonym denomination Agrobacterium tumefaciens. In order to study the relative distribution of Agrobacterium strains according to their origins, we performed a multilocus sequence-based analysis (MLSA) on a large collection of 89 clinical and environmental strains from various origins. We proposed an MLSA scheme based on the partial sequence of 7 housekeeping genes (atpD, zwf, trpE, groEL, dnaK, glnA, and rpoB) present on the circular chromosome of A. tumefaciens C58. Multilocus phylogeny revealed that 88% of the clinical strains belong to genovar A7, which formed a homogeneous population with linkage disequilibrium, suggesting a low rate of recombination. Comparison of genomic fingerprints obtained by pulsed-field gel electrophoresis (PFGE) showed that the strains of genovar A7 were epidemiologically unrelated. We present genetic evidence that genovar A7 may constitute a human-associated population distinct from the environmental population. Also, phenotypic characteristics, such as culture at 42°C, agree with this statement. This human-associated population might represent a potential novel species in the genus Agrobacterium.
authors.affiliation: Université Montpellier 1, Unité Mixte de Recherche 5119 Ecosym, Equipe Pathogènes et Environnements, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 5, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Aujoulat
authors.forename: Estelle
authors.initials: E
authors.lastname: Jumas-Bilak
authors.forename: Agnès
authors.initials: A
authors.lastname: Masnou
authors.forename: Fanny
authors.initials: F
authors.lastname: Sallé
authors.forename: Denis
authors.initials: D
authors.lastname: Faure
authors.forename: Christine
authors.initials: C
authors.lastname: Segonds
authors.forename: Hélène
authors.initials: H
authors.lastname: Marchandin
authors.forename: Corinne
authors.initials: C
authors.lastname: Teyssier
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004783:Environmental Microbiology; D005838:Genotype; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012231:Rhizobium / Q000145:classification* / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial