title: Mesorhizobium metallidurans sp. nov., a metal-resistant symbiont of Anthyllis vulneraria growing on metallicolous soil in Languedoc, France.
abstract: A polyphasic taxonomic approach was used to characterize 31 rhizobial isolates obtained from Anthyllis vulneraria, a metallicolous legume species, growing close to a zinc mine in the south of France (Saint Laurent le Minier). Comparative analysis of nearly full-length 16S rRNA gene sequences showed that these Gram-negative bacteria belonged to the genus Mesorhizobium and that they were related most closely to Mesorhizobium tianshanense ORS 2640(T). The phylogenetic relationships of these isolates with other Mesorhizobium species were confirmed by sequencing and analysis of the recA and atpD genes, which were used as alternative chromosomal markers. These novel mesorhizobial strains tolerated high concentrations of heavy metals: 16-32 mM Zn and 0.3-0.5 mM Cd. DNA-DNA hybridizations revealed >73 % relatedness between the strains isolated from A. vulneraria, but only 19-33 % relatedness between these and the type strains of M. tianshanense and Mesorhizobium mediterraneum. These results, together with other phenotypic characteristics, support the conclusion that these isolates represent a single, novel species of the genus Mesorhizobium, for which the name Mesorhizobium metallidurans sp. nov. is proposed. The type strain is STM 2683(T) (=CFBP 7147(T)=LMG 24485(T)).
authors.affiliation: INRA, USC1242, Laboratoire des Symbioses Tropicales et Méditerranéennes, Campus International de Baillarguet TA A-82/J, F-34398, Montpellier Cedex 5, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Vidal
authors.forename: Clémence
authors.initials: C
authors.lastname: Chantreuil
authors.forename: Odile
authors.initials: O
authors.lastname: Berge
authors.forename: Lucette
authors.initials: L
authors.lastname: Mauré
authors.forename: José
authors.initials: J
authors.lastname: Escarré
authors.forename: Gilles
authors.initials: G
authors.lastname: Béna
authors.forename: Brigitte
authors.initials: B
authors.lastname: Brunel
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Cleyet-Marel