Sideroxyarcus emersonii gen. nov. sp. nov., a neutrophilic, microaerobic iron- and thiosulfate-oxidizing bacterium isolated from iron-rich wetland sediment

A neutrophilic iron-oxidizing bacterium, strain MIZ01T, which was previously isolated from a wetland in Ibaraki, Japan, was taxonomically characterized in detail. Strain MIZ01T was a motile, curved-rod shaped, Gram-stain-negative bacterium. It was able to grow at 10-40 °C (optimally at 30-35 °C) and at pH 5.5-7.0 (optimally at pH 6.0). It grew microaerobically and chemolithoautotrophically using thiosulfate, in addition to ferrous iron, as the sole electron donor. Major cellular fatty acids of strain MIZ01T were C16 : 1 ω7c/C16 : 1 ω6c and C16 : 0. The complete genome sequence (2.74 Mbp) was determined, showing that its DNA G+C content was 60.0 mol%. Phylogenetic analyses indicated that strain MIZ01T belonged to the family Gallionellaceae, class Betaproteobacteria, and was closely related to an isolate tentatively named 'Sideroxydans lithotrophicus' ES-1 (98.2 % of 16S rRNA gene sequence similarity). Based on its phenotypic and phylogenetic characteristics, we conclude that strain MIZ01T represents a new genus and species in the family Gallionellaceae for which we propose the name Sideroxyarcus emersonii gen. nov., sp. nov. The type strain is strain MIZ01T (=JCM 39089T=DSM 111897T).