Deferribacter abyssi sp. nov., an anaerobic thermophile from deep-sea hydrothermal vents of the Mid-Atlantic Ridge

1 Institute of Microbiology, Russian Academy of Sciences, Prospekt 60-letiya Oktyabrya 7/2, Moscow 117811, Russia 2 UMR 6539, Centre National de la Recherche Scientifique and Université de Bretagne Occidentale, Institut Universitaire Européen de la Mer, 29280 Plouzané, France 3 DSMZ – Deutsche Sammlung von Mikroorganismen und Zellkulturen, Mascheroder Weg 1b, 38124 Braunschweig, Germany Correspondence M. L. Miroshnichenko alfamirr{at}mail.ru Two strains of thermophilic, anaerobic, chemolithoautotrophic bacteria, designated JR T and DR, were isolated from hydrothermal samples collected on the Mid-Atlantic Ridge from the Rainbow (36° 16' N, 33° 54' W) and Menez Gwen (37° 50' N, 31° 50' W) vent fields, respectively. Cells of both isolates were short, straight- to vibrio-shaped, motile rods with one polar flagellum, and were Gram-negative and non-sporulating. Strain JR T was characterized in detail. It was found to grow optimally at pH 6·5–6·7, at 60 °C and in the presence of 30 g NaCl l -1 . Strain JR T could use molecular hydrogen, acetate, succinate, pyruvate and proteinaceous compounds as electron donors, and elemental sulfur, nitrate or Fe(III) as electron acceptors. No fermentation of organic substrates occurred. The G+C content of the DNA of strain JR T was 30·8 mol%. Strain DR (=DSM 14927) possessed the same morphology and pH, temperature and salinity optima and ranges, and used the same electron acceptors as strain JR T . On the basis of their 16S rDNA sequences (1517 nucleotides), strains JR T and DR were identical and distantly related to Deferribacter thermophilus and Deferribacter desulfuricans (95·3 and 95·2 % sequence similarity, respectively). Based on their phenotypic and phylogenetic characteristics, it is proposed that both strains are members of a new species of the genus Deferribacter , for which the name Deferribacter abyssi (type strain JR T =DSM 14873 T =JCM 11955 T ) is proposed. The GenBank accession numbers for the 16S rDNA sequences of Deferribacter abyssi strains JR T and DR are AJ515882 and AJ515881 , respectively.