Taxonomic characterization of Sphaerotilus microaerophilus sp. nov., a sheath-forming microaerophilic bacterium of activated sludge origin

• Published in: Archives of microbiology 2024-06, Vol.206 (6), p.252-252, Article 252
• Main Authors: Narihara, Shiori, Chida, Shun, Matsunaga, Naoki, Akimoto, Ryosuke, Akimoto, Mizuki, Hagio, Aoi, Mori, Tomomi, Nittami, Tadashi, Sato, Michio, Mun, Sehui, Kang, Hyeonjin, Back, Ji Hwan, Takeda, Minoru
• Format: Article
• Language: English
• Subjects: Activated sludge; Amino acids; Bacteria; Bacterial Typing Techniques; Base Composition; Biochemistry; Biomedical and Life Sciences; Biotechnology; carbon; Carbon sources; Catalase; Cell Biology; DNA; DNA, Bacterial - genetics; Ecology; energy; Fatty Acids - analysis; Flagella; flagellum; genes; Genome, Bacterial; Genomes; Genomics; genus; Japan; Life Sciences; Microbial Ecology; Microbiology; New species; Organic acids; Original Paper; Peptides; Phylogeny; Quinones; RNA, Ribosomal, 16S - genetics; rRNA 16S; Sequence Analysis, DNA; Sewage - microbiology; Sheaths; species; Sphaerotilus; Strains (organisms); Sulfur; temperature; Vitamin B12
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-024-03991-9

A microaerophilic Gram-stain-negative bacilliform bacterial strain, FB-5  T , was isolated from activated sludge in Yokohama, Japan, that exhibited filamentous growth and formed a microtube (sheath). Cells were motile using a single polar flagellum. The optimum growth temperature and pH were 30 °C and 7.5, respectively. Strain FB-5  T was catalase-negative. Peptides and amino acids were utilized as energy and carbon sources. Sugars and organic acids were not utilized. Vitamin B 12 enhanced the growth of strain FB-5  T . Sulfur-dependent lithotrophic growth was possible. Major respiratory quinone was UQ-8. Major fatty acids were C 16:1 ω7 and C 16:0 . The genomic DNA G + C content was 69.16%. Phylogenetic analysis of the 16S rRNA gene suggested that strain FB-5  T belongs to the genus Sphaerotilus . The close relatives were S. natans subsup. sulfidivorans and S. natans subsup. natans with 98.0% and 97.8% similarity based on the 16S rRNA gene analysis, respectively. The genome size (6.06 Mbp) was larger than that (4.39–5.07 Mbp) of the Sphaerotilus strains. The AAI values against the related strains ranged from 71.0 to 72.5%. The range of ANI values was 81.7 − 82.5%. In addition to these distinguishable features of the genome, the core genome and dDDH analyses suggested that this strain is a novel member of the genus Sphaerotilus . Based on its physiological properties and genomic features, strain FB-5  T is considered as a novel species of the genus Sphaerotilus , for which the name S. microaerophilus sp. nov. is proposed. The type strain is FB-5  T (= JCM 35424  T  = KACC 23146  T ).