Spirosoma Linguale Research Articles

Morphological change of coiled bacterium Spirosoma linguale with acquisition of \u03b2-lactam resistance

Spirosoma linguale is a gram-negative, coiled bacterium belonging to the family Cytophagaceae. Its coiled morphology is unique in contrast to closely related bacteria belonging to the genus Spirosoma, which have a short, rod-shaped morphology. The mechanisms that generate unique cell morphology are still enigmatic. In this study, using the Spirosoma linguale ATCC33905 strain, we isolated β-lactam (cefoperazone and amoxicillin)-resistant clones. These clones showed two different cell morphological changes: relatively loosely curved cells or small, horseshoe-shaped cells. Whole-genome resequencing analysis revealed the genetic determinants of β-lactam resistance and changes in cell morphology. The loose-curved clones commonly had mutations in Slin_5958 genes encoding glutamyl-tRNA amidotransferase B subunit, whereas the small, horseshoe-shaped clones commonly had mutations in either Slin_5165 or Slin_5509 encoding pyruvate dehydrogenase (PDH) components. Two clones, CFP1ESL11 and CFL5ESL4, which carried only one mutation in Slin_5958, showed almost perfectly straight, rod-shaped cells in the presence of amoxicillin. This result suggests that penicillin-binding proteins targeted by amoxicillin play an important role in the formation of a coiled morphology in this bacterium. In contrast, supplementation with acetate did not rescue the growth defect and abnormal cell size of the CFP5ESL9 strain, which carried only one mutation in Slin_5509. These results suggest that PDH is involved in cell-size maintenance in this bacterium.

Enzymatic Conversion of RBCs by α-N-Acetylgalactosaminidase from Spirosoma linguale.

Spirosoma linguale is a free-living nonpathogenic organism. Like many other bacteria, S. linguale produces a cell-associated α-N-acetylgalactosaminidase. This work was undertaken to elucidate the nature of this activity. The recombinant enzyme was produced, purified, and examined for biochemical attributes. The purified enzyme was ~50 kDa active as a homodimer in solution. It catalyzed hydrolysis of α-N-acetylgalactosamine at pH 7. Calculated KM was 1.1 mM with kcat of 173 s−1. The described enzyme belongs to the GH109 family.

Spirosoma pomorum sp. nov., isolated from apple orchard soil

A Gram-negative, motile, rod-shaped, aerobic bacterial strain, designated S7-2-11T, was isolated from apple orchard soil from Gyeongsangnam-do Province, Republic of Korea, and was characterized taxonomically using a polyphasic approach. 16S rRNA gene sequence analysis indicated that strain S7-2-11T belongs to the family Cytophagaceae in phylum Bacteroidetes, and is closely related to Spirosoma luteolum 16F6ET (94.2% identity), Spirosoma knui 15J8-12T (92.7%), and Spirosoma linguale DSM 74T (91.0%). The G + C content of the genomic DNA of strain S7-2-11T was 49.8 mol%. Strain S7-2-11T contained summed feature 3 (C16:1 ω7c/C16:1 ω6c; 35.1%), C16:1 ω5c (22.4%), C15:0 iso (13.9%), and C17:0 iso 3-OH (10.6%) as major cellular fatty acids, and MK-7 as the predominant respiratory quinone. The main polar lipids were phosphatidylethanolamine, an unidentified aminophospholipid, and two unidentified polar lipids. Phenotypic and chemotaxonomic data supported the affiliation of strain S7-2-11T with the genus Spirosoma. The results of physiological and biochemical tests showed the genotypic and phenotypic differentiation of the isolate from recognized Spirosoma species. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain S7-2-11T represents a novel species of the genus Spirosoma, for which the name Spirosoma pomorum sp. nov. is proposed. The type strain is S7-2-11T (= KCTC 52726T = JCM 32130T).

Spirosoma horti sp. nov., isolated from apple orchard soil.

A Gram-negative, motile by gliding, rod-shaped, aerobic bacterium, designated S7-3-19T, was isolated from apple orchard soil in Gyeongsangnam-do Province, Republic of Korea, and characterized taxonomically by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequencing showed that strain S7-3-19T belonged to the family Cytophagaceae and was most closely related to Spirosoma linguale DSM 74T (96.38 %), Spirosoma fluviale MSd3T (96.38 %), Spirosoma pulveris JSH5-14T (96.35 %) and Spirosoma radiotolerans DG5AT (96.24 %). Chemotaxonomic characteristics supported the classification of strain S7-3-19T within the genus Spirosoma. Summed feature 3 (C16 : 1ω7c/C16 : 1ω6c; 46.7 %) and C16 : 1ω5c (23.8 %) were the major fatty acids. Phosphatidylethanolamine, an unidentified aminophospholipid, an unidentified phospholipid and two unidentified lipids were the major polar lipids. Menaquinone with seven isoprene units was the predominant respiratory quinone. The G+C content of the genomic DNA of strain S7-3-19T was 48.6 mol%. On the basis of its phenotypic properties, genotypic distinctiveness and chemotaxonomic features, strain S7-3-19T represents a novel species of the genus Spirosoma, for which the name Spirosomahorti sp. nov. is proposed. The type strain is S7-3-19T (=KCTC 52728T=JCM 32131T).

Spirosoma agri sp. nov., Isolated from Apple Orchard Soil.

A Gram-negative, non-motile, rod-shaped, aerobic bacterial strain, designated S7-3-3T, was isolated from apple orchard soil in Gyeongsangnam-do province, South Korea, and was characterized taxonomically using a polyphasic approach. Phylogenetic analysis based on 16SrRNA gene sequence showed that strain S7-3-3T belonged to the family Cytophagaceae in the phylum Bacteroidetes was most closely related to Spirosoma rigui WPCB118T (94.3%), Spirosoma pulveris JSH5-14T (93.9%), and Spirosoma linguale DSM 74T (93.7%). The strain showed typical chemotaxonomic characteristics of the genus Spirosoma with a predominant respiratory quinone of menaquinone MK-7 and the major fatty acids of summed feature 3 (C16:1 ω7c/C16:1 ω6c; 43.9%) and C16:1 ω5c (25.6%). The G+C content of genomic DNA was 49.6mol%. The polar lipid profile contained major amounts of phosphatidylethanolamine, an unidentified aminophospholipid, and an unidentified polar lipid. Phenotypic and chemotaxonomic data supported the affiliation of strain S7-3-3T with the genus Spirosoma. The results of physiological and biochemical tests showed the genotypic and phenotypic differentiation of the isolate from recognized Spirosoma species. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain S7-3-3T represents a novel species of the genus Spirosoma, for which the name Spirosoma agri sp. nov. is proposed. The type strain is S7-3-3T (= KCTC 52727T = JCM 32199T).

Spirosoma migulaei sp. nov., isolated from soil.

A Gram-stain-negative, non-motile, non-spore-forming, rod-shaped, aerobic bacterium, designated 15J9-8T, was isolated from soil on Jeju Island, Republic of Korea. The isolate was able to grow between 10 and 30°C, pH 6.5-8.5, and in presence of 0-1% (w/v) NaCl. The results of comparative 16S rRNA gene sequence analysis indicated that strain 15J9-8T represented a member of the family Cytophagaceae, phylum Bacteroidetes, and was most closely related to Spirosoma aerophilum 5516J-17T (96.1% similarity), Spirosoma pulveris JSH5-14T (95.6%), and Spirosoma linguale DSM 74T (95.2%). The G + C content of the genomic DNA of the isolate was 47.0 mol%. Strain 15J9-8T contained summed feature 3 (C16:1 ω7c/C16:1 ω6c), C16:1 ω5c, and iso-C15:0 as the major fatty acids, phosphatidylethanolamine and an unidentified aminophospholipid as the main polar lipids, and menaquinone MK-7 as the predominant respiratory quinone. On the basis of its phenotypic and genotypic properties, and phylogenetic distinctiveness, strain 15J9-8T should be classified as a representative of a novel species of the genus Spirosoma, for which the name Spirosoma migulaei sp. nov. is proposed. The type strain is 15J9-8T (=KCTC 52028T =JCM 31996T).

Spirosoma jeollabukense sp. nov., isolated from soil.

A Gram-negative, non-motile, rod-shaped, aerobic bacterial strain, designated S2-3-6T, was isolated from soil in Jeollabuk-do province, South Korea, and was characterized taxonomically using a polyphasic approach. According to a comparative 16S rRNA gene sequence analysis, strain S2-3-6T belonged to the family Cytophagaceae and was most closely related to Spirosoma endophyticum EX36T (98.2%), Spirosoma fluviale MSd3T (96.0%), and Spirosoma linguale DSM 74T (95.7%). Strain S2-3-6T contained summed feature 3 (C16:1 ω7c/C16:1 ω6c), C16:1 ω5c, and C16:0N alcohol as major cellular fatty acids, MK-7 as the predominant respiratory quinone, and phosphatidylethanolamine as the main polar lipid. The DNA G+C content of strain S2-3-6T was 47.8%. Phenotypic and chemotaxonomic data supported the affiliation of strain S2-3-6T to the genus Spirosoma. However, the DNA-DNA relatedness between strain S2-3-6T and Spirosoma endophyticum KACC 17920T was 27%, clearly showing that the isolate constitutes a new genospecies. Strain S2-3-6T could be clearly differentiated from its closest neighbors based on its phenotypic, genotypic, and chemotaxonomic features. Therefore, strain S2-3-6T represents a novel species of the genus Spirosoma, for which the name Spirosoma jeollabukense sp. nov. is proposed. The type strain is S2-3-6T (= KCTC 52725T = JCM 32129T).

Spirosoma humi sp. nov., Isolated from Soil in South Korea.

A Gram-stain-negative, non-motile, rod-shaped, aerobic bacterial strain, designated S7-4-1T, was isolated from soil in Gyeongsangnam-do, South Korea and characterized using a polyphasic approach to determine its taxonomic position. Phylogenic analysis based on the 16S rRNA gene sequence showed that strain S7-4-1T belonged to the family Cytophagaceae and was most closely related to Spirosoma fluviale MSd3T (96.2%), 'Spirosoma radiotolerans' DG5A (96.0%), Spirosoma pulveris JSH5-14T (95.9%), and Spirosoma linguale DSM 74T (95.8%). The G+C content of the genomic DNA of the isolate was 49.0mol%. The strain contained summed feature 3 (C16:1 ω7c/C16:1 ω6c; 41.0%), C16:1 ω5c (24.9%), and C15:0 iso (9.3%) as the major fatty acids, menaquinone MK-7 as the predominant respiratory quinone, and phosphatidylethanolamine and an unidentified aminophospholipid as the main polar lipids, which supported its affiliation with the genus Spirosoma. The results of physiological and biochemical tests allowed the genotypic and phenotypic differentiation of the isolate from recognized Spirosoma species. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain S7-4-1T represents a novel species of the genus Spirosoma, for which the name Spirosoma humi sp. nov. is proposed. The type strain is S7-4-1T (= KCTC 52729T = JCM 32132T).

Spirosoma lituiforme sp. nov., isolated from soil.

A Gram-staining-negative, non-motile, curved rod-shaped, aerobic bacterium, designated S1-2-4T, was isolated from soil in Jeollabuk-do province, Republic of Korea, and was characterized taxonomically using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain S1-2-4T was a member of the family Cytophagaceae and most closely related to 'Spirosoma radiotolerans' DG5A (97.2%), Spirosoma fluviale MSd3T (96.4%), and Spirosoma linguale DSM 74T (96.3%). The genomic DNA G + C content of strain S1-2-4T was 49.7 mol%. The major fatty acids were summed feature 3 (C16:1 ω7c/C16:1 ω6c), C16:1 ω5c, and C16:0, and the major polar lipid was phosphatidylethanolamine. MK-7 was the predominant respiratory quinone. Phenotypic and chemotaxonomic data supported the affiliation of strain S1-2-4T with the genus Spirosoma. DNA-DNA hybridization between strain S1-2-4T and 'Spirosoma radiotolerans' showed relatively low DNA-DNA relatedness (31%). Strain S1-2-4T could be distinguished from its closest phylogenetic neighbors based on its phenotypic, genotypic, and chemotaxonomic features. Therefore, strain S1-2-4T represents a novel member of the genus Spirosoma, for which the name Spirosoma lituiforme sp. nov. is proposed. The type strain is S1-2-4T (= KCTC 52724T = JCM 32128T).

Spirosoma metallum sp. nov., isolated from an automobile air conditioning system

A Gram-stain-negative and yellow-pigmented bacterial strain, designated TX0653T, was isolated from an automobile evaporator core collected in Korea. The cells were aerobic and rod-shaped. The strain grew at 10-28°C (optimum, 25°C), at pH 6.0-7.5 (optimum, 6.5), and in the presence of 0-1% (w/v) NaCl (optimum, 0%). Phylogenetically, the strain was related to members of the genus Spirosoma (95.1-90.8% 16S rRNA sequence similarity) and distantly related to Spirosoma pulveris JSH5-14T (95.1%), Spirosoma fluviale MSd3T (95.0%), Spirosoma endophyticum DSM 26130T (94.8%), and Spirosoma linguale DSM 74T (94.6%). The major fatty acids of the strain were summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), C16:1 ω5c, iso-C15:0, iso-C17:0 3-OH, and C16:0. MK-7 was identified as the predominant menaquinone. The polar lipids profile indicated the presence of one phosphatidylethanolamine, one unidentified aminolipid, one unidentified aminophospholipid, two unidentified phospholipids, and three unidentified lipids. On the basis of the phenotypic, genotypic, and chemotaxonomic characteristics, strain TX0653T represents a novel species in the genus Spirosoma, for which the name Spirosoma metallum sp. nov. (=KACC 19278T=NBRC 112495T) is proposed.

Spirosoma aerophilum sp. nov., isolated from an air sample.

A rod-shaped, yellow, Gram-stain-negative, non-flagellated, aerobic bacterium, designated 5516J-17T, was isolated from an air sample collected from Jeju Island, Republic of Korea. It grew in the temperature range of 10-37 °C (optimum 28-30 °C), pH 6.0-11.0 (optimum, pH 7.0) and 0-1 % NaCl (w/v). Phylogenetic trees generated using 16S rRNA gene sequences revealed that strain 5516J-17T belongs to the genus Spirosoma, showing 96.9 % sequence similarity to the most closely related species, Spirosoma linguale DSM 74T. The cellular fatty acids comprised large amounts (>10 % of total fatty acids) of summed feature 3 (C16:1ω7c and/or C16:1ω6c) and C16:1ω5c, and moderate amounts (5-10 % of total fatty acids) of iso-C17:0 3-OH, iso-C15:0 and C16:0. The DNA G+C content was 55.7 mol % and MK-7 was the predominant isoprenoid quinone. Polar lipids were phosphatidylethanolamine, two unknown aminophospholipids, one unknown aminolipid and one unknown lipid. On the basis of this phenotypic and polyphasic taxonomy study, it is suggested that strain 5516J-17T represents a novel species within the genus Spirosoma, with the proposed name Spirosoma aerophilum. The type strain is 5516J-17T (= KACC 17323T = DSM 28388T = JCM 19950T).

Spirosoma fluviale sp. nov., isolated from river water.

A bacterial strain, designated MSd3T, was isolated from a freshwater sample collected from the Hosoda River in Japan. The cells of strain MSd3T were Gram-stain-negative, non-spore-forming, aerobic, non-motile, curved rods forming rings, coils and undulating filaments. The 16S rRNA gene sequence of strain MSd3T showed closest similarity to that of Spirosoma linguale DSM 74T (97.6 % similarity) and similarity to other members of the genus Spirosoma ranged from 90.3 to 95.9 %. Strain MSd3T contained menaquinone 7 as the sole respiratory quinone. The major cellular fatty acids were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) and C16 : 1ω5c. The polar lipids were phosphatidylethanolamine, three unidentified aminophospholipids and three unidentified polar lipids. The DNA G+C content was 53.3 mol%. The DNA-DNA relatedness between strain MSd3T and S. linguale DSM 74T was 19 % or 25 % (reciprocal value). From the chemotaxonomic and physiological data and the levels of DNA-DNA relatedness, strain MSd3T should be classified as the representative of a novel species of the genus Spirosoma, for which the name Spirosoma fluviale sp. nov. (type strain MSd3T = JCM 30659T = DSM 29961T) is proposed.

Spirosoma radiotolerans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil.

A Gram-negative, short-rod-shaped bacterial strain with gliding motility, designated as DG5A(T), was isolated from a rice field soil in South Korea. Phylogenic analysis using 16S rRNA gene sequence of the new isolate showed that strain DG5A(T) belong to the genus Spirosoma in the family Spirosomaceae, and the highest sequence similarities were 95.5 % with Spirosoma linguale DSM 74(T), 93.4 % with Spirosoma rigui WPCB118(T), 92.8 % with Spirosoma luteum SPM-10(T), 92.7 % with Spirosoma spitsbergense SPM-9(T), and 91.9 % with Spirosoma panaciterrae Gsoil 1519(T). Strain DG5A(T) revealed resistance to gamma and UV radiation. Chemotaxonomic data showed that the most abundant fatty acids were summed feature C(16:1) ω7c/C(16:1) ω6c (36.90 %), C(16:1) ω5c (29.55 %), and iso-C(15:0) (14.78 %), and the major polar lipid was phosphatidylethanolamine (PE). The DNA G+C content of strain DG5A(T) was 49.1 mol%. Together, the phenotypic, phylogenetic, and chemotaxonomic data supported that strain DG5A(T) presents a novel species of the genus Spirosoma, for which the name Spirosoma radiotolerans sp. nov., is proposed. The type strain is DG5A(T) (=KCTC 32455(T) = JCM19447(T)).

Identification and Characterization of Cellobiose 2-Epimerases from Various Aerobes

Cellobiose 2-epimerase (CE), found mainly in anaerobes, reversibly converts D-glucose residues at the reducing end of β-1,4-linked oligosaccharides to D-mannose residues. In this study, we characterized CE-like proteins from various aerobes (Flavobacterium johnsoniae NBRC 14942, Pedobacter heparinus NBRC 12017, Dyadobacter fermentans ATCC 700827, Herpetosiphon aurantiacus ATCC 23779, Saccharophagus degradans ATCC 43961, Spirosoma linguale ATCC 33905, and Teredinibacter turnerae ATCC 39867), because aerobes, more easily cultured on a large scale than anaerobes, are applicable in industrial processes. The recombinant CE-like proteins produced in Escherichia coli catalyzed epimerization at the C2 position of cellobiose, lactose, epilactose, and β-1,4-mannobiose, whereas N-acetyl-D-glucosamine, N-acetyl-D-mannosamine, D-glucose, and D-mannose were inert as substrates. All the CEs, except for P. heparinus CE, the optimum pH of which was 6.3, showed highest activity at weakly alkaline pH. CEs from D. fermentans, H. aurantiacus, and S. linguale showed higher optimum temperatures and thermostability than the other enzymes analyzed. The enzymes from D. fermentans, S. linguale, and T. turnerae showed significantly high k(cat) and K(m) values towards cellobiose and lactose. Especially, T. turnerae CE showed a very high k(cat) value towards lactose, an attractive property for the industrial production of epilactose, which is carried out at high substrate concentrations.

Interspecies variation in survival and growth of filamentous heterotrophic bacteria in response to UVC radiation

Ultraviolet radiation is an important environmental constraint on the evolution of life. In addition to its harmful effects, ultraviolet radiation plays an important role in generating genetic polymorphisms and acting as a selective agent. Understanding how prokaryotes cope with high radiation can give insights on the evolution of life on Earth. Four representative filamentous bacteria from the family Cytophagaceae with different pigmentation were selected and exposed to different doses of UVC radiation (15–32,400 J m −2). The effect of UVC radiation on bacterial survival, growth and morphology were investigated. Results showed high survival in response to UVC for Rudanella lutea and Fibrisoma limi, whereas low survival was observed for Fibrella aestuarina and Spirosoma linguale. S. linguale showed slow growth recovery after ultraviolet exposure, R. lutea and F. limi showed intermediate growth recovery, while F. aestuarina had the fastest recovery among the four tested bacteria. In terms of survival, S. linguale was the most sensitive bacterium whereas R. lutea and F. limi were better at coping with UVC stress. The latter two resumed growth even after 2 h exposure (∼10,800 J m −2). Additionally, the ability to form multicellular filaments after exposure was tested using two bacteria: one representative of the high ( R. lutea) and one of the low ( F. aestuarina) survival rates. The ability to elongate filaments due to cell division was preserved but modified. In R. lutea 10 min exposure reduced the average filament length. The opposite was observed in F. aestuarina, where the 5 and 10 min exposures increased the average filament length. R. lutea and F. limi are potential candidates for further research into survival and resistance to ultraviolet radiation stress.

Complete genome sequence of Spirosoma linguale type strain (1T)

Spirosoma linguale Migula 1894 is the type species of the genus. S. linguale is a free-living and non-pathogenic organism, known for its peculiar ringlike and horseshoe-shaped cell morphology. Here we describe the features of this organism, together with the complete genome sequence and annotation. This is only the third completed genome sequence of a member of the family Cytophagaceae. The 8,491,258 bp long genome with its eight plasmids, 7,069 protein-coding and 60 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.

Fibrella aestuarina gen. nov., sp. nov., a filamentous bacterium of the family Cytophagaceae isolated from a tidal flat, and emended description of the genus Rudanella Weon et al. 2008

A Gram-staining-negative, pink bacterium, designated strain BUZ 2(T), was isolated from coastal mud from the North Sea (Fedderwardersiel, Germany). Cells were rod-shaped and able to form multicellular filaments. Growth after 7 days was observed at 10-40 °C, at pH 6-8 and with 0-0.5 % NaCl. The phylogenetic tree based on 16S rRNA gene sequences indicated that strain BUZ 2(T) is a member of the family Cytophagaceae, its closest neighbours being Rudanella lutea 5715S-11(T), Spirosoma linguale LMG 10896(T) and Spirosoma panaciterrae Gsoil 1519(T) (87.8, 86.4 and 86.1 % sequence similarity, respectively). The major fatty acids were summed feature 3 (comprising C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH), C(16 : 1)ω5c and iso-C(15 : 0). The predominant respiratory quinone was MK-7 and the major polar lipids were phosphatidylethanolamine and several unidentified aminophospholipids. The DNA G+C content was 56.5 mol%. On the basis of this polyphasic study, we propose that strain BUZ 2(T) represents a novel genus and species, for which the name Fibrella aestuarina gen. nov., sp. nov. is proposed. The type strain of Fibrella aestuarina is BUZ 2(T) (=DSM 22563(T) =CCUG 58136(T)). An emended description of the genus Rudanella is also proposed.

Spirosoma spitsbergense sp. nov. and Spirosoma luteum sp. nov., isolated from a high Arctic permafrost soil, and emended description of the genus Spirosoma

Two pigmented, Gram-negative, non-motile, pleomorphic rod-shaped bacteria (strains SPM-9(T) and SPM-10(T)) were isolated from a permafrost soil collected from the Adventdalen valley, Spitsbergen, northern Norway. A third isolate (strain M5-H2) was recovered from the same soil sample after the sample had been exposed to simulated Martian environmental conditions. The three strains were characterized taxonomically by using a polyphasic approach. Phylogenetic, chemotaxonomic, physiological and morphological analyses demonstrated that the three isolates were most closely related to members of the genus Spirosoma. 16S rRNA gene sequence data indicated that the three isolates could be divided into two clusters: (i) strain SPM-9(T) and (ii) strains SPM-10(T) and M5-H2. This grouping was confirmed by DNA-DNA hybridization experiments. Strains SPM-9(T) and SPM-10(T) exhibited 92 % 16S rRNA gene sequence similarity to both Spirosoma linguale LMG 10896(T) and Spirosoma rigui WPCB 118(T). The major fatty acids present in all three isolates were summed feature 3 (comprising iso-C(15:0) 2-OH and/or C(16 : 1)omega7c; 43.0-48.2 % of the total), C(16 : 1)omega5c (19.1-21.3 %), C(16 : 0) (6.7-7.3 %), iso-C(17 : 0) 3-OH (4.7-6.0 %) and iso-C(15 : 0) (2.6-5.7 %). On the basis of their phenotypic and genotypic characteristics, the new strains are assigned to two novel species of the genus Spirosoma, for which the names Spirosoma spitsbergense sp. nov. and Spirosoma luteum sp. nov. are proposed. The type strain of Spirosoma spitsbergense is SPM-9(T) (=NCIMB 14407(T)=DSM 19989(T)) and the type strain of Spirosoma luteum is SPM-10(T) (=NCIMB 14406(T)=DSM 19990(T)). An emended description of the genus Spirosoma is also proposed.

Spirosoma panaciterrae sp. nov., isolated from soil

A Gram-negative, yellowish bacterial strain, designated Gsoil 1519(T), was isolated from soil of a ginseng field in Pocheon province (South Korea) and characterized using a polyphasic approach to determine its taxonomic position. Comparative 16S rRNA gene sequence analysis showed that strain Gsoil 1519(T) belongs to the family 'Flexibacteraceae' and is related to Spirosoma rigui KCTC 12531(T) (91.8 % similarity) and Spirosoma linguale LMG 10896(T) (91.5 % similarity). Phylogenetic distances from any other recognized species within the family 'Flexibacteraceae' were greater than 14.7 %. The G+C content of the genomic DNA of strain Gsoil 1519(T) was 50.1 %. The detection of MK-7 as the predominant menaquinone and a fatty acid profile with C(16 : 1)omega5c, summed feature 4 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH), iso-C(15 : 0) and C(16 : 0) as the major acids supported the affiliation of strain Gsoil 1519(T) to the genus Spirosoma. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain Gsoil 1519(T) should be classified in the genus Spirosoma as a representative of a novel species, for which the name Spirosoma panaciterrae sp. nov. is proposed. The type strain is Gsoil 1519(T) (=KCTC 22263(T)=DSM 21099(T)).

Rudanella lutea gen. nov., sp. nov., isolated from an air sample in Korea

An orange-coloured bacterial strain, designated 5715S-11(T), was isolated from an air sample in Suwon, Republic of Korea. The strain was strictly aerobic, Gram-negative, non-spore-forming, non-flagellated and rod-shaped, frequently forming filaments. Growth of the strain was observed at 4-40 degrees C (optimum, 30 degrees C), pH 6.0-8.0 (optimum, pH 7.0) and 0-2 % (w/v) NaCl. Phylogenetically, strain 5715S-11(T) was shown to be a member of the family Spirosomaceae within the phylum Bacteroidetes. Its closest relatives were Spirosoma linguale LMG 10896(T) (87.9 % 16S rRNA gene sequence similarity) and Larkinella insperata LMG 22510(T) (86.2 % 16S rRNA gene sequence similarity). Predominant cellular fatty acids were summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH), C(16 : 1)omega5c and iso-C(15 : 0). Major polar lipids were phosphatidylethanolamine and unknown aminolipids and polar lipids. On the basis of the evidence from this polyphasic study, strain 5715S-11(T) is considered to represent a novel species of a new genus, for which the name Rudanella lutea gen. nov., sp. nov. is proposed. The type strain of Rudanella lutea is 5715S-11(T) (=KACC 12603(T) =DSM 19387(T)).