Sphaerotilus uruguayifluvii sp. nov., a novel filamentous bacterium isolated from river water

Strain C29^T, a Gram-staining-negative, straight rod occurring singly, in pairs or short chains, was isolated from floating filamentous biomass of the Uruguay River. The strain was catalase and oxidase positive, chemoorganotrophic, strictly aerobic, non-motile, and grew at pH 6.0-9.0, 15-45 °C, and 0-0.5% (w/v) NaCl. Polyhydroxybutyrate was accumulated in nutrient-limited conditions. Phylogenetic analysis based on the 16S rRNA gene revealed that strain C29^T had the highest sequence similarity with Leptothrix discophora SS-1^T (97.82%), Ideonella livida TBM-1^T (97.82%), Vitreoscilla filiformis L1401-2^T (97.52%), Sphaerotilus sulfidivorans D-501^T (97.50%) and Sphaerotilus natans DSM 6575^T (97.46%). Other type strains with validly published names had similarities below 97.46%. Further phylogenomic analysis showed that strain C29^T was affiliated to the family Sphaerotilaceae. Average nucleotide identity (ANI) and in silico DNA-DNA hybridization (dDDH) values with its phylogenetic relatives were lower than 91 and 41%, respectively, revealing that strain C29^T represented a new species. The DNA G + C content of strain C29^T was 70.9%. The annotation of the genome of the novel strain shows it possessed genes for the degradation of aromatic compounds. It also contained genes that encode sigma factors involved in response regulation of stress resistance, which is an important function for adaptation and survival in natural niches. Based on the results of the phylogenetic and phenotypic analyses, we propose that strain C29^T represents a novel species, for which the name Sphaerotilus uruguayifluvii sp. nov. is proposed. The type strain is C29^T (= CCM 9043^T = DSM 113250^T).