Sulfurimicrobium lacus gen. nov., sp. nov., a sulfur oxidizer isolated from lake water, and review of the family Sulfuricellaceae to show that it is not a later synonym of Gallionellaceae

A facultatively anaerobic sulfur-oxidizing bacterium, strain skT11 T , was isolated from anoxic lake water of a stratified freshwater lake. As electron donor for chemolithoautotrophic growth, strain skT11 T oxidized thiosulfate, tetrathionate, and elemental sulfur under nitrate-reducing conditions. Oxygen-dependent growth was observed under microoxic conditions, but not under fully oxygenated conditions. Growth was observed at a temperature range of 5–37 °C, with optimum growth at 28 °C. Strain skT11 T grew at a pH range of 5.1–7.5, with optimum growth at pH 6.5–6.9. Heterotrophic growth was not observed. Major components in the cellular fatty acid profile were C 16:1 and C 16:0 . The complete genome of strain skT11 T consisted of a circular chromosome with a size of 3.8 Mbp and G + C content of 60.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the strain skT11 T is related to sulfur-oxidizing bacteria of the genera Sulfuricella , Sulfurirhabdus, and Sulfuriferula , with sequence identities of 95.4% or lower. The analysis also indicated that these three genera should be excluded from the family Gallionellaceae , as members of another family. On the basis of its genomic and phenotypic properties, strain skT11 T (= DSM 110711 T = NBRC 114323 T ) is proposed as the type strain of a new species in a new genus, Sulfurimicrobium lacus gen. nov., sp. nov. In addition, emended descriptions of the families Gallionellaceae and Sulfuricellaceae are proposed to declare that Sulfuricellaceae is not a later synonym of Gallionellaceae .