title: Caldinitratiruptor microaerophilus, gen. nov., sp. nov. isolated from a French hot spring (Chaudes-Aigues, Massif Central): a novel cultivated facultative microaerophilic anaerobic thermophile pertaining to the Symbiobacterium branch within the Firmicutes.
abstract: A novel facultative microaerophilic nitrate-reducing bacterium designated CA62N(T) was isolated from a thermal spring in France. Cells were non-motile rods (2-3 x 0.2 mum) and showed low cytoplasmic density when observed under a phase-contrast microscope. Strain CA62N(T) grew at temperatures between 50 and 75 degrees C (optimum 65 degrees C) and at a pH between 6.3 and 7.9 (optimum 7.0). NaCl was not required for growth but was tolerated up to 10 gl(-1). Sulfate, thiosulfate, elemental sulfur, sulfite, and nitrite were not used as electron acceptors. Nitrate was reduced to nitrite. Strain CA62N(T) used lactate, pyruvate, glucose, mannose, fructose, and casamino acids and some amino acids as electron donors only in the presence of nitrate as electron acceptor. None of these substrates was fermented. The main end-products of glucose oxidation were acetate, CO(2), and traces of H(2). The G + C content of the genomic DNA was 70.3 mol% (HPLC techniques). Phylogenetic analysis of the small-subunit (SSU) ribosomal RNA (rRNA) gene sequence indicated that strain CA62N(T) was affiliated to the Symbiobacterium branch within the Firmicutes and had Symbiobacterium thermophilum and "S. toebii" as its closest phylogenetic relatives. On the basis of phylogenetical and physiological characteristics, strain CA62N(T) is proposed to be the type strain for the novel species in the novel genus, Caldinitratiruptor microaerophilus gen. nov., sp. nov. (DSM 22660, JCM 16183).
authors.affiliation: Laboratoire de Microbiologie IRD, UMR 180, Universités de Provence et de la Méditerranée, ESIL case 925, 163 Avenue de Luminy, 13288, Marseille Cedex 9, France.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Fardeau
authors.forename: Vanessa
authors.initials: V
authors.lastname: Barsotti
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Cayol
authors.forename: Sophie
authors.initials: S
authors.lastname: Guasco
authors.forename: Valérie
authors.initials: V
authors.lastname: Michotey
authors.forename: Manon
authors.initials: M
authors.lastname: Joseph
authors.forename: Patricia
authors.initials: P
authors.lastname: Bonin
authors.forename: Bernard
authors.initials: B
authors.lastname: Ollivier
mesh_terms: D001421:Bacteria, Anaerobic / Q000235:genetics*; D001482:Base Composition / Q000235:genetics; D017753:Ecosystem; D019143:Evolution, Molecular; D005602:France; D019015:Geologic Sediments; D045482:Hot Springs / Q000382:microbiology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008854:Microscopy, Electron / Q000379:methods; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013696:Temperature