Thiomicrorhabdus immobilis sp. nov., a mesophilic sulfur-oxidizing bacterium isolated from sediment of a brackish lake in northern Japan

A novel sulfur-oxidizing bacterium, strain Am19 T , was isolated from sediment of a brackish lake. Strain Am19 T grew chemolithoautotrophically on inorganic sulfur compounds, and heterotrophic growth was not observed. Cells were rod-shaped with length of 1.1–3.0 μm and diameter of 0.5–0.8 μm. Growth was observed at 5–37 °C with an optimum growth temperature of 30 °C. The pH range for growth was 5.6–8.5 with an optimum pH of 6.6–7.0. Major fatty acids were summed feature 3 (C 16: 1 ω7c and/or C 16: 1 ω6c), summed feature 8 (C 18: 1 ω7c and/or C 18: 1 ω6c) and C 16: 0 . The sole respiratory quinone was ubiquinone-8. The complete genome of strain Am19 T is composed of a circular chromosome with length of 2.5 Mbp and G + C content of 42.7 mol%. Phylogenetic analysis based on genomic data indicated that strain Am19 T belongs to the genus Thiomicrorhabdus but is distinct from any existing species. Analysis of the 16S rRNA gene supported creation of a new species to accommodate strain Am19 T . On the basis of genomic and phenotypic characteristics, strain Am19 T (= NBRC 114602 T = BCRC 81336 T ) is proposed as the type strain of a new species, with name of Thiomicrorhabdus immobilis sp. nov.