Isolation of Spirosoma foliorum sp. nov. from the fallen leaf of Acer palmatum by a novel cultivation technique

In the effort of isolating novel microbial species, the strain PL0132T was isolated from a fallen leaf under fresh water at a stream, which glided when grown on a tap water medium (without nutrients). The strain was determined to be Gram-negative, strictly aerobic, and rod-shaped, which grew optimally at 25 °C, pH 6-7, and the strain tolerates 1% (w/v) NaCl concentration. The complete genome of strain PL0132T comprises one contig with a sequencing depth of 76×, consisting of 8,853,064 base pairs and the genomic DNA G + C content was 46.7% (genome). 16S rRNA gene sequence analysis revealed that strain PL0132T represents a member of the phylum Bacteroidetes and is affiliated with the genus Spirosoma. Based on genomic, phenotypic, and chemotaxonomic characteristics, the strain PL0132T represents a novel species of the genus Spirosoma, for which the name Spirosoma foliorum sp. nov. is proposed (= KCTC 72228 T = InaCC B1447T).

Spirosoma rhododendri sp. nov., isolated from a flower of royal azalea (Rhododendron schlippenbachii)

A Gram-negative, non-motile, strictly aerobic and rod- or filamentous-shaped strain, CJU-R4T, was isolated from a flower of royal azalea (Rhododendron schlippenbachii) collected in the Republic of Korea. Strain CJU-R4T was catalase-positive and oxidase-negative, and grew at 15–33 °C (optimum, 28–20 °C), at pH 5.0–8.0 (optimum, pH 7.0–8.0), and in the presence of 0–1 % NaCl (w/v; optimum, 0 %). Strain CJU-R4T had the highest 16S rRNA gene sequence similarity to Spirosoma oryzae RHs22T (96.6 %), revealing less than 93 % sequence similarity to other type strains. Phylogenetic and phylogenomic analysis also revealed strain CJU-R4T formed a robust cluster with S. oryzae RHs22T. The major fatty acids were summed feature 3 (comprising C16 : 1  ω7c and/or C16 : 1  ω6c; 33.0 %), C16 : 1  ω5c (22.1 %), iso-C15 : 0 (12.6 %) and C16 : 0 (10.7 %). The polar lipids were composed of phosphatidylethanolamine, three unidentified aminophospholipids, one unidentified phospholipid and four unidentified lipids. Menaquinone-7 was detected as the sole respiratory quinone. The genomic DNA G+C content was 55.2 mol%. The average nucleotide identity and digital DNA–DNA hybridization values between strain CJU-R4T and Spirosoma oryzae DSM 28354T were 81.5 and 23.9 %, respectively. Based on the results of the phenotypic and genotypic analyses, strain CJU-R4T is considered to represent a novel species of the genus Spirosoma , for which the name Spirosoma rhododendri sp. nov. is proposed. The type strain is CJU-R4T (=KACC 21264T=NBRC 114513T).

Spirosoma utsteinense sp. nov. isolated from Antarctic ice-free soils from the Utsteinen region, East Antarctica

Between 2014 and 2016, 16 Gram-stain-negative, aerobic, rod-shaped and yellow-orange pigmented bacteria were isolated from exposed soils from the Utsteinen region, Sør Rondane Mountains, East Antarctica. Analysis of their 16S rRNA gene sequences revealed that the strains form a separate cluster in the genus Spirosoma, with Spirosoma rigui KCTC 12531^T as its closest neighbour (97.8 % sequence similarity). Comparative genome analysis of two representative strains (i.e. R-68523^T and R-68079) of the new group with the type strains of Spirosoma rigui (its closest neighbour) and Spirosoma linguale (type species of the genus), yielded average nucleotide identity values of 73.9-78.7 %. Digital DNA-DNA reassociation values of the two strains and these type strains ranged from 20.3 to 22.0 %. The predominant cellular fatty acids of the two novel strains were summed feature 3 (i.e. C_16 : 1  ω7c and/or iso-C₁₅ 2-OH), C_16 : 1  ω5c, C_16 : 0 and iso-C_15 : 0. The new Spirosoma strains grew with 0-0.5 % (w/v) NaCl, at pH 6.5-8.0 and displayed optimum growth between 15 and 25 °C. Based on the results of phenotypic, genomic, phylogenetic and chemotaxonomic analyses, the new strains represent a novel species of the genus Spirosoma for which the name Spirosoma utsteinense sp. nov. is proposed. The type strain is R-68523^T (=LMG 31447^T=CECT 9925^T).

Spirosoma endbachense sp. nov., isolated from a natural salt meadow

A Gram-stain-negative bacterium, designated I-24^T, was isolated from soil of a natural salt meadow. Strain I-24^T was aerobic, non-motile, rod-shaped, catalase-positive, oxidase-positive and grew optimally at pH 7 and 25 °C. Comparative 16S rRNA gene analysis indicated that strain I-24^T has closest similarities to Spirosoma agri KCTC 52727^T (95.9 %) and Spirosoma terrae KCTC 52035^T (95.5 %). Strain I-24^T contained summed feature 3 (C_16 : 1  ω7c/C_16 : 1  ω6c) and C_16 : 1  ω5c as the major fatty acids, the predominant respiratory quinone was menaquinone MK-7, and the major polar lipids were phosphatidylethanolamine as well as an unidentified phosphoaminolipid. The draft genome of strain I-24^T consists of 10 326 072 base pairs with 9153 predicted coding sequences and a G+C content of 47.7 mol%. Clear distinctions between strain I-24^T and S. agri KCTC 52727^T or S. terrae KCTC 52035^T were shown in the pairwise average nucleotide identity results with values of 76.71 and 74.01 %, respectively. Moreover, the digital DNA-DNA relatedness values to these strains were 20.8 and 19.0 %. Based on its phenotypic, genotypic and chemotaxonomic characteristics, strain I-24^T represents a novel species of the genus Spirosoma, for which the name Spirosoma endbachense sp. nov. is proposed. The type strain is I-24^T (DSM 111055^T=KCTC 72613^T).

Draft Genome Sequences of Spirosoma agri KCTC 52727 and Spirosoma terrae KCTC 52035

Spirosoma agri S7-3-3 (KCTC 52727) and Spirosoma terrae 15J9-4 (KCTC 52035) are type strains isolated from an apple orchard and beach soil in South Korea, respectively; their draft genome sequences were assembled and annotated. The draft genome sequences of S7-3-3^T (7,239,915 bp; G+C content, 50.6%) and 15J9-4^T (7,551,610 bp; G+C content, 47.3%) are reported.

Spirosoma agri S7-3-3 (KCTC 52727) and Spirosoma terrae 15J9-4 (KCTC 52035) are type strains isolated from an apple orchard and beach soil in South Korea, respectively; their draft genome sequences were assembled and annotated. The draft genome sequences of S7-3-3^T (7,239,915 bp; G+C content, 50.6%) and 15J9-4^T (7,551,610 bp; G+C content, 47.3%) are reported.