Spirosoma migulaei sp. nov., isolated from soil

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).

Fibrivirga algicola gen. nov., sp. nov., an algicidal bacterium isolated from a freshwater river

An aerobic, gram-stain-negative, pink-colored, non-motile and rod-shaped algicidal bacterium, designated as JA-25^T was isolated from freshwater in Geumgang River, Republic of Korea. Strain JA-25^T grew at 15-30 °C and pH 6-9, and did not require NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JA-25^T belongs to the family 'Spirosomaceae' and is most closely related to Fibrella aestuarina BUZ 2^T (93.6%). Strain JA-25^T showed < 90% sequence similarity to other members of the family 'Spirosomaceae'. The average nucleotide identity(ANI), in silico DNA-DNA hybridization and average amino acid identity(AAI) values based on the genomic sequences of JA-25^T and F. aestuarina BUZ 2^T were 74.4, 20.5, and 73.6%, respectively. Strain JA-25^T showed an algicidal effect on the marine flagellate alga Heterocapsa triquetra, but no effect on fresh water cyanobacterium (Nostoc). In genome analysis, RIPP-like peptides were detected and predicted to resemble the indolmycin biosynthetic gene cluster, which possibly influence its algicidal effect. Furthermore, a bacteriorhodopsin gene with photoheterotrophic characteristics was detected. The genomic DNA G + C content was 52.5 mol%. The major cellular fatty acids were summed feature 3 (C16:1 ω6c/C16:1 ω7c), C16:1 ω5c, C16:0 (> 10%). The major respiratory quinone was menaquinone 7 and major polar lipids were phosphatidylethanolamine, two unidentified aminolipids, two phospholipids, and five unidentified lipids. Considering the phylogenetic inference, phenotypic, and chemotaxonomic data, strain JA-25^T should be classified as a novel species in the novel genus Fibrivirga, with the proposed name Fibrivirga algicola sp. nov. The type strain is JA-25^T (= KCCM 43334^T = NBRC 114259^T).

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 telluris sp. nov. and Spirosoma arboris sp. nov. isolated from soil and tree bark, respectively

Two novel strains (HMF3257T and HMF4905T), isolated from freshwater and bark samples, were investigated to determine their relationships within and between species of the genus Spirosoma by using a polyphasic approach. They were aerobic, Gram-stain-negative, non-motile and rod-shaped bacteria. The major fatty acids (>10%) in both strains were identified as summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and C16 : 1 ω5c, while strains HMF3257T and HMF4905T contained a moderately high amount of C16 : 0 and iso-C15 : 0, respectively. The predominant respiratory quinone was MK-7 for both strains. In addition to phosphatidylethanolamine and one unidentified glycolipid, the polar lipid profile of strain HMF3257T consisted of three unidentified aminophospholipids, one unidentified aminolipid and two unidentified polar lipids, and that of strain HMF4905T consisted of one unidentified aminophospholipid, two unidentified aminolipids and three unidentified polar lipids. The DNA G+C contents of strains HMF3257T and HMF4905T were 47.2 and 46.4 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains HMF3257T and HMF4905T are closely related to Spirosoma migulaei 15J9-8T (97.0 % sequence similarity), while sharing 97.4 % sequence similarity with each other. The average nucleotide identity value between strains HMF3257T and HMF4905T was 81.1 %, and the digital DNA–DNA hybridization value between these two strains was 24.4 %. Based on the above data, strains HMF3257T and HMF4905T represent two novel members within the genus Spirosoma , for which the names Spirosoma telluris sp. nov. and Spirosoma arboris sp. nov. are proposed, respectively. The type strain of S. telluris is HMF3257T (=KCTC 62463T=NBRC 112670T) and type strain of S. arboris is HMF4905T (=KCTC 72779T=NBRC 114270T).

Complete Genome Sequence of Spirosoma sp. Strain KCTC 42546, Isolated from a Reservoir in South Korea

This study reports on the complete genome sequence of Spirosoma sp. strain KCTC 42546, isolated from fresh water in a reservoir in South Korea. The genome contained genes for various glycosyl hydrolases, which are associated with degrading sugars and DNA-repairing enzymes.

This study reports on the complete genome sequence of Spirosoma sp. strain KCTC 42546, isolated from fresh water in a reservoir in South Korea. The genome contained genes for various glycosyl hydrolases, which are associated with degrading sugars and DNA-repairing enzymes.