title: Rhizobium metallidurans sp. nov., a symbiotic heavy metal resistant bacterium isolated from the Anthyllis vulneraria Zn-hyperaccumulator.
abstract: A Gram-stain-negative, aerobic, rod-shaped, non-spore-forming bacterium (ChimEc512(T)) was isolated from 56 host seedlings of the hyperaccumulating Anthyllis vulneraria legume, which was on an old zinc mining site at Les Avinières, Saint-Laurent-Le-Minier, Gard, South of France. On the basis of 16S rRNA gene sequence similarities, strain ChimEc512(T) was shown to belong to the genus Rhizobium and to be most closely related to Rhizobium endophyticum CCGE 2052(T) (98.4%), Rhizobium tibeticum CCBAU 85039(T) (98.1%), Rhizobium grahamii CCGE 502(T) (98.0%) and Rhizobium mesoamericanum CCGE 501(T) (98.0%). The phylogenetic relationships of ChimEc512(T) were confirmed by sequencing and analyses of recA and atpD genes. DNA-DNA relatedness values of strain ChimEc512(T) with R. endophyticum CCGE 2052(T), R. tibeticum CCBAU 85039(T), R. mesoamericanum CCGE 52(T), Rhizobium grahamii CCGE 502(T), Rhizobium etli CCBAU 85039(T) and Rhizobium radiobacter KL09-16-8-2(T) were 27, 22, 16, 18, 19 and 11%, respectively. The DNA G+C content of strain ChimEc512(T) was 58.9 mol%. The major cellular fatty acid was C18 : 1ω7c, characteristic of the genus Rhizobium . The polar lipid profile included phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol and phosphatidylcholine and moderate amounts of aminolipids, phospholipid and sulfoquinovosyl diacylglycerol. Although ChimEc512(T) was able to nodulate A. vulneraria, the nodC and nifH genes were not detected by PCR. The rhizobial strain was tolerant to high concentrations of heavy metals: up to 35 mM Zn and up to 0.5 mM Cd and its growth kinetics was not impacted by Zn. The results of DNA-DNA hybridizations and physiological tests allowed genotypic and phenotypic differentiation of strain ChimEc512(T) from species of the genus Rhizobium with validly published names. Strain ChimEc512(T), therefore, represents a novel species, for which the name Rhizobium metallidurans sp. nov. is proposed, with the type strain ChimEc512(T) ( =DSM 26575 = CIP 110550(T)).
authors.affiliation: Environmental Research Institute, Lee road, University College Cork, Cork, Ireland.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Grison
authors.affiliation: Environmental Research Institute, Lee road, University College Cork, Cork, Ireland.
authors.forename: Stephen
authors.initials: S
authors.lastname: Jackson
authors.affiliation: Institut des Sciences du Végétal, CNRS, UPR 2355, Bât. 22, 1 avenue de la terrasse, 91198 Gif-sur-Yvette cedex, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Merlot
authors.affiliation: Environmental Research Institute, Lee road, University College Cork, Cork, Ireland.
authors.forename: Alan
authors.initials: A
authors.lastname: Dobson
authors.affiliation: FRE 3673 - Bioinspired chemistry and ecological innovation - CNRS, University of Montpellier 2, Stratoz - Cap Alpha, Avenue de l'Europe 34830 Clapiers, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Grison
mesh_terms: D015373:Bacterial Typing Techniques; D001482:Base Composition; D004269:DNA, Bacterial / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology*; D005227:Fatty Acids / Q000737:chemistry; D005602:France; D008906:Mining; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010743:Phospholipids / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012231:Rhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D013559:Symbiosis; D015032:Zinc
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S; D015032:Zinc