A novel bacterium, strain MOT50^T, was isolated from the chimney structure at the Iheya North field in the Mid-Okinawa Trough. The cells were motile short rods with a single polar flagellum. Growth was observed between 40 and 65 ℃ (optimum, 52 ℃), at pH values between 5.0 and 7.1 (optimum, pH 6.1) and in the presence of 2.0–4.0% NaCl (optimum, 2.5%). The isolates utilized molecular hydrogen, thiosulfate, or elemental sulfur as the sole electron donor. Thiosulfate, elemental sulfur, nitrate, and molecular oxygen are utilized as the sole electron acceptor. Ammonium is required as a nitrogen source. Thiosulfate, elemental sulfur, sulfate, or sulfite serves as a sulfur source for growth. The G + C content of the genomic DNA was 28.9%. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain MOT50^T belonged to the genus Nitrosophilus of the class “Campylobacteria”, and its closest relative was Nitrosophilus labii HRV44^T (97.20%). On the basis of the phylogenetic, physiological, and molecular characteristics, it is proposed that the organism represents a novel species within the genus Nitrosophilus, Nitrosophilus kaiyonis sp. nov. The type strain is MOT50^T (= JCM 39187^T = KCTC 25251^T).

一种新型细菌，菌株 MOT50 ^T，与冲绳中部海槽 Iheya North 油田的烟囱结构分离。细胞是具有单极鞭毛的活动短杆。在 40 至 65 ℃（最佳，52 ℃）、pH 值介于 5.0 和 7.1（最佳，pH 6.1）之间以及存在 2.0–4.0% NaCl（最佳，2.5%）的条件下观察到生长。这些分离物利用分子氢、硫代硫酸盐或元素硫作为唯一的电子供体。硫代硫酸盐、元素硫、硝酸盐和分子氧被用作唯一的电子受体。需要铵作为氮源。硫代硫酸盐、元素硫、硫酸盐或亚硫酸盐用作生长的硫源。基因组DNA的G+C含量为28.9%。基于16S rRNA基因序列的系统发育分析表明菌株MOT50 ^T属于该属“弯曲杆菌”类的亚硝化嗜酸菌，其最亲近的亲属是Nitrosophilus labii HRV44 ^T (97.20%)。根据系统发育、生理和分子特征，提出该生物代表亚硝化菌属中的一个新物种，Nitrosophilus kaiyonis sp。十一月 类型应变为 MOT50 ^T（= JCM 39187 ^T  = KCTC 25251 ^T）。