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We studied a solid-solution system of the transition-metal pnictide, Y₂(MnxFe₁−x)₁₂P₇, with the Zr₂Fe₁₂P₇-type structure, which has two kinds of transition metal sites: three tetrahedral sites and a pyramidal site. We successfully obtained polycrystalline samples of Y₂(MnxFe₁−x)₁₂P₇ in the range of 0 ≦ x ≦ 0.9. The lattice parameter along the a-axis monotonically increases with the Mn substitution, while that along the c-axis is nearly constant. ⁵⁷Fe Mössbauer spectroscopy shows that Mn atoms prefer to occupy the pyramidal site. At x = 0.25, the site-ordered compound, Y₂Mn₃Fe₉P₇, was obtained, where Mn atoms occupy the pyramidal site and Fe atoms occupy the tetrahedral sites. The magnetization of Y₂Mn₃Fe₉P₇ exhibits an anomaly at approximately 60 K, suggesting presence of an antiferromagnetic transition, which originates from the magnetic moment of Mn at the pyramidal site.

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Shiotani, T., Mino, S., Sato, W., Nishikawa, S., Yonezawa, M., Sievert, S. M., & Sawabe, T. Nitrosophilus alvini gen. nov., sp. nov., a hydrogen-oxidizing chemolithoautotroph isolated from a deep-sea hydrothermal vent in the East Pacific Rise, inferred by a genome-based taxonomy of the phylum "Campylobacterota". Plos One, 15(12), (2020): e0241366, doi:10.1371/journal.pone.0241366., A novel bacterium, strain EPR55-1T, was isolated from a deep-sea hydrothermal vent on the East Pacific Rise. The cells were motile rods. Growth was observed at temperatures between 50 and 60°C (optimum, 60°C), at pH values between 5.4 and 8.6 (optimum, pH 6.6) and in the presence of 2.4–3.2% (w/v) NaCl (optimum, 2.4%). The isolate used molecular hydrogen as its sole electron donor, carbon dioxide as its sole carbon source, ammonium as its sole nitrogen source, and thiosulfate, sulfite (0.01 to 0.001%, w/v) or elemental sulfur as its sole sulfur source. Nitrate, nitrous oxide (33%, v/v), thiosulfate, molecular oxygen (0.1%, v/v) or elemental sulfur could serve as the sole electron acceptor to support growth. Phylogenetic analyses based on both 16S rRNA gene sequences and whole genome sequences indicated that strain EPR55-1T belonged to the family Nitratiruptoraceae of the class “Campylobacteria”, but it had the distinct phylogenetic relationship with the genus Nitratiruptor. On the basis of the physiological and molecular characteristics of the isolate, the name Nitrosophilus alvini gen. nov. sp. nov. is proposed, with EPR55-1T as the type strain (= JCM 32893T = KCTC 15925T). In addition, it is shown that “Nitratiruptor labii” should be transferred to the genus Nitrtosophilus; the name Nitrosophilus labii comb. nov. (JCM 34002T = DSM 111345T) is proposed for this organism. Furthermore, 16S rRNA gene-based and genome-based analyses showed that Cetia pacifica is phylogenetically associated with Caminibacter species. We therefore propose the reclassification of Cetia pacifica as Caminibacter pacificus comb. nov. (DSM 27783T = JCM 19563T). Additionally, AAI thresholds for genus classification and the reclassification of subordinate taxa within “Campylobacteria” are also evaluated, based on the analyses using publicly available genomes of all the campylobacterial species., This study was partially supported by the JSPS KAKENHI (No. 12J03037 and No. 15H05991), the Takahashi Industrial and Economic Research Foundation, and US National Science Foundation grant OCE-1559198 and the WHOI Investment in Science Fund to S.M.S. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

A novel thermophilic bacterium, strain SSM-sur55(T), was isolated from a chimney structure at the Urashima site on the Southern Mariana Trough in the Pacific Ocean. Growth was observed at temperatures between 25 and 60 degrees C (optimum, 55 degrees C; 180 min doubling time), at pH values between 5.3 and 7.2 (optimum, pH 5.9) and in the presence of between 1.6 and 5.6% (w/v) NaCl (optimum, 3.2%). The isolate used molecular hydrogen as its sole energy source, carbon dioxide as its sole carbon source, ammonium as its sole nitrogen source, and elemental sulfur as its sole sulfur source. Thiosulfate, molecular oxygen (0.1%, v/v) or elemental sulfur was utilized as its sole electron acceptor. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SSM-sur55(T) belonged to the genus Hydrogenimonas of the class "Campylobacteria", and its closest relative was Hydrogenimonas thermophila EP1-55-1%(T) (94.9%). On the basis of the phylogenetic, physiological and molecular characteristics, strain SSM-sur55(T) represents a novel species within the genus Hydrogenimonas, for which the name Hydrogenimonas urashimensis sp. nov. is proposed, with the type strain SSM-sur55(T) (JCM 19825 = KCTC 15926).

A novel thermophilic bacterium, strain SSM-sur55(T), was isolated from a chimney structure at the Urashima site on the Southern Mariana Trough in the Pacific Ocean. Growth was observed at temperatures between 25 and 60 degrees C (optimum, 55 degrees C; 180 min doubling time), at pH values between 5.3 and 7.2 (optimum, pH 5.9) and in the presence of between 1.6 and 5.6% (w/v) NaCl (optimum, 3.2%). The isolate used molecular hydrogen as its sole energy source, carbon dioxide as its sole carbon source, ammonium as its sole nitrogen source, and elemental sulfur as its sole sulfur source. Thiosulfate, molecular oxygen (0.1%, v/v) or elemental sulfur was utilized as its sole electron acceptor. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SSM-sur55(T) belonged to the genus Hydrogenimonas of the class "Campylobacteria", and its closest relative was Hydrogenimonas thermophila EP1-55-1%(T) (94.9%). On the basis of the phylogenetic, physiological and molecular characteristics, strain SSM-sur55(T) represents a novel species within the genus Hydrogenimonas, for which the name Hydrogenimonas urashimensis sp. nov. is proposed, with the type strain SSM-sur55(T) (JCM 19825 = KCTC 15926).

A novel bacterium, strain EPR55-1(T), was isolated from a deep-sea hydrothermal vent on the East Pacific Rise. The cells were motile rods. Growth was observed at temperatures between 50 and 60 degrees C (optimum, 60 degrees C), at pH values between 5.4 and 8.6 (optimum, pH 6.6) and in the presence of 2.4-3.2% (w/v) NaCl (optimum, 2.4%). The isolate used molecular hydrogen as its sole electron donor, carbon dioxide as its sole carbon source, ammonium as its sole nitrogen source, and thiosulfate, sulfite (0.01 to 0.001%, w/v) or elemental sulfur as its sole sulfur source. Nitrate, nitrous oxide (33%, v/v), thiosulfate, molecular oxygen (0.1%, v/v) or elemental sulfur could serve as the sole electron acceptor to support growth. Phylogenetic analyses based on both 16S rRNA gene sequences and whole genome sequences indicated that strain EPR55-1(T) belonged to the family Nitratiruptoraceae of the class "Campylobacteria", but it had the distinct phylogenetic relationship with the genus Nitratiruptor. On the basis of the physiological and molecular characteristics of the isolate, the name Nitrosophilus alvini gen. nov. sp. nov. is proposed, with EPR55-1(T) as the type strain (= JCM 32893(T) = KCTC 15925(T)). In addition, it is shown that "Nitratiruptor labii" should be transferred to the genus Nitrtosophilus; the name Nitrosophilus labii comb. nov. (JCM 34002(T) = DSM 111345(T)) is proposed for this organism. Furthermore, 16S rRNA gene-based and genome-based analyses showed that Cetia pacifica is phylogenetically associated with Caminibacter species. We therefore propose the reclassification of Cetia pacifica as Caminibacter pacificus comb. nov. (DSM 27783(T) = JCM 19563(T)). Additionally, AAI thresholds for genus classification and the reclassification of subordinate taxa within "Campylobacteria" are also evaluated, based on the analyses using publicly available genomes of all the campylobacterial species.