Bacterial gasdermins reveal an ancient mechanism of cell death.

Gasdermin proteins form large membrane pores in human cells that release immune cytokines and induce lytic cell death. Gasdermin pore formation is triggered by caspase-mediated cleavage during inflammasome signaling and is critical for defense against pathogens and cancer. We discovered gasdermin homologs encoded in bacteria that defended against phages and executed cell death. Structures of bacterial gasdermins revealed a conserved pore-forming domain that was stabilized in the inactive state with a buried lipid modification. Bacterial gasdermins were activated by dedicated caspase-like proteases that catalyzed site-specific cleavage and the removal of an inhibitory C-terminal peptide. Release of autoinhibition induced the assembly of large and heterogeneous pores that disrupted membrane integrity. Thus, pyroptosis is an ancient form of regulated cell death shared between bacteria and animals.

Hymenobacter radiodurans sp. nov., isolated from soil in the Republic of Korea.

A bacterial strain, designated 17J36-26T, was isolated from the UV-irradiated soil from Jeju Island, South Korea. Cells are Gram negative, strictly aerobic, non-motile, non-spore forming, rod shaped, and catalase and oxidase positive. The major fatty acids of strain 17J36-26T were summed feature 4 (17:1 iso I/17:1 anteiso B), summed feature 3 (16:1 ω6c/16:1 ω7c), C16:1 ω5c and iso-C15:0. The polar lipid profile contained phosphatidylethanolamine, unidentified aminophospholipid, phospholipids and four unidentified lipids. The G+C content of the strain 17J36-26T was 62.6 mol%. The 16S rRNA gene sequence analysis showed that strain 17J36-26T was phylogenetically related to Hymenobacter qilianensis DK6-37T and Hymenobacter roseosalivarius AA718T (97.5% and 96.8% sequence similarity, respectively). Strain 17J36-26T showed resistance to UV radiation. Both average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between strains 17J36-26T and type strains of Hymenobacter species were lower than the cut-off (≥ 95-96% for ANI and ≥ 70% for isDDH) to define a bacterial new species. The polyphasic approach using genotypic, phenotypic and chemotaxonomic data showed that strain 17J36-26T could be distinguished from its phylogenetically related species, and thus, the strain representative of a novel species within the genus Hymenobacter, for which the name Hymenobacter radiodurans sp. nov. (type strain 17J36-26T = KCTC 62269T = JCM 33185T) is proposed.

Dyadobacter luteus sp. nov., isolated from rose rhizosphere soil.

A novel Gram-negative, aerobic, rod-shaped bacterium, RS19T, was isolated from rose rhizosphere soil. The strain was psychrophilic and showed good growth over a temperature range of 1-37 â„ƒ. Colonies on TSB agar were circular, smooth, mucoid, convex with clear edges and yellow. Phylogenetic analysis based on 16S rRNA gene sequences characterized RS19T in the genus Dyadobacter and showed that strain RS19T was most closely related to Dyadobacter psychrophilus CGMCC 1.8951T (97.4%) and Dyadobacter alkalitolerans CGMCC 1.8973T (97.1%). The average nucleotide identity values to the closest related species type strains were less than 84.0%. The DNA G + C content was 43.1 mol%, and the predominant respiratory menaquinone was MK-7. The major fatty acids were summed features 3 (C16:1ω7c and/or C16:1ω6c), iso-C15:0, C16:1ω5c and iso-C17:0 3-OH. Based on genotypic, phenotypic and chemotaxonomic data, strain RS19T is different from closely related species of the genus Dyadobacter. RS19T represents a novel species within the genus Dyadobacter, for which the name Dyadobacter luteus sp. nov. is proposed. The type strain is RS19T (= CGMCC 1.13719T = ACCC 60381T = JCM 32940T).

Structure-Function Analysis of the Phosphoesterase Component of the Nucleic Acid End-Healing Enzyme Runella slithyformis HD-Pnk.

Runella slithyformis HD-Pnk is the prototype of a family of dual 5' and 3' nucleic acid end-healing enzymes that phosphorylate 5'-OH termini and dephosphorylate 2',3'-cyclic-PO4, 3'-PO4, and 2'-PO4 ends. HD-Pnk is composed of an N-terminal HD phosphohydrolase module and a C-terminal P-loop polynucleotide kinase module. Here, we probed the phosphoesterase activity of HD-Pnk by querying its ability to hydrolyze non-nucleic acid phosphoester substrates and by conducting a mutational analysis of conserved amino acid constituents of the HD domain. We report that HD-Pnk catalyzes vigorous hydrolysis of p-nitrophenylphosphate (Km = 3.13 mM; kcat = 27.8 s-1) using copper as its metal cofactor. Mutagenesis identified Gln28, His33, His73, Asp74, Lys77, His94, His127, Asp162, and Arg166 as essential for p-nitrophenylphosphatase and DNA 3' phosphatase activities. Structural modeling places these residues at the active site, wherein His33, His73, Asp74, His94, and His127 are predicted to coordinate a binuclear metal complex and Lys77 and Arg166 engage the scissile phosphate. HD-Pnk homologs are distributed broadly (and exclusively) in bacteria, usually in a two-gene cluster with a putative ATP-dependent polynucleotide ligase (LIG). We speculate that HD-Pnk and LIG comprise the end-healing and end-sealing components of a bacterial nucleic acid repair pathway.IMPORTANCE 5'-end healing and 3'-end healing are key steps in nucleic acid break repair in which 5'-OH ends are phosphorylated by a polynucleotide kinase, and 3'-PO4 or 2',3'-cyclic-PO4 ends are hydrolyzed by a phosphoesterase to generate 5'-PO4 and 3'-OH termini needed for joining by DNA and RNA ligases. This study interrogates, biochemically and via mutagenesis, the phosphoesterase activity of Runella slithyformis HD-Pnk, a bifunctional bacterial 5'- and 3'-end-healing enzyme composed of HD phosphoesterase and P-loop kinase modules. HD-Pnk homologs are found in 129 bacterial genera from 11 phyla. In 123/129 instances, HD-Pnk is encoded in an operon-like gene cluster with a putative ATP-dependent polynucleotide ligase (LIG), suggesting that HD-Pnk and LIG are agents of a conserved bacterial nucleic acid repair pathway.

Hymenobacter segetis sp. nov., isolated from soil.

A polyphasic taxonomic study was performed on a novel strain designated as S7-3-11T, which was isolated from soil of the Gyeongsangnam-do province in Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain S7-3-11T belongs to the genus Hymenobacter and is most closely related to Hymenobacter ruber PB156T (97.9%), Hymenobacter daeguensis 16F3Y-2T (97.8%), Hymenobacter glaciei VUG-A130T (97.7%), Hymenobacter soli PB17T (97.5%), Hymenobacter terrae DG7AT (97.5%), and Hymenobacter antarcticus VUG-A42aaT (97.3%). However, DNA-DNA hybridization results showed less than 50% relatedness with respect to the type strains of the six most closely related species. The DNA G + C content of strain S7-3-11T was 60.2 mol%. MK-7 was identified as the predominant respiratory quinone, and summed feature 3 (C16:1 ω7c/C16:1 ω6c; 21.5%), C15:0 iso (16.8%), C15:0 anteiso (16.2%), and C15:1 iso G (10.8%) were the major fatty acids. Phosphatidylethanolamine, an unidentified aminolipid, and an unidentified aminophospholipid were detected as major polar lipids. On the basis of the polyphasic evidence presented, strain S7-3-11T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter segetis sp. nov. is proposed. The type strain is S7-3-11T (= KCTC 52732T = JCM 32197T).

Hymenobacter jeollabukensis sp. nov., isolated from soil.

A Gram-stain-negative, non-motile, rod-shaped, aerobic bacterial strain, designated 1-3-3-8T, was isolated from soil and characterized taxonomically using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain 1-3-3-8T belongs to the family Cytophagaceae of phylum Bacteroidetes and is most closely related to Hymenobacter paludis KBP-30T (96.8% similarity), Hymenobacter ocellatus Myx2105T (96.8%), Hymenobacter coalescens WW84T (95.6%), and Hymenobacter deserti ZLB-3T (95.4%). The G + C content of the genomic DNA of strain 1-3-3-8T was 63.6 mol%. The isolate contained C15:0 iso (28.4%), summed feature 4 (C17:1 anteiso B/C17:1 iso I; 18.9%), and C15:0 anteiso (17.6%) as major fatty acids, MK-7 as the predominant respiratory quinone, and sym-homospermidine as the predominant polyamine. The major polar lipids were phosphatidylethanolamine and an unidentified lipid. The phenotypic and chemotaxonomic data supported the affiliation of strain 1-3-3-8T with the genus Hymenobacter. The DNA-DNA relatedness between strain 1-3-3-8T and H. paludis KCTC 32237T and H. ocellatus DSM 11117T were 24.5 and 27.4% respectively, clearly showing that the isolate is not related to them at the species level. Overall, the novel strain could be differentiated from its phylogenetic neighbors on the basis of several phenotypic, genotypic, and chemotaxonomic features. Therefore, strain 1-3-3-8T represents a novel species of the genus Hymenobacter, for which the name Hymenobacter jeollabukensis sp. nov. has been proposed. The type strain is 1-3-3-8T (= KCTC 52741T = JCM 32192T).

Hymenobacter agri sp. nov., a novel bacterium isolated from soil.

A bacterial isolate was recovered from a soil sample collected in Jeollabuk-do Province, South Korea, and subjected to polyphasic taxonomic assessment. Cells of the isolate, designated strain S1-2-1-2-1T, were observed to be rod-shaped, pink in color, and Gram-stain negative. The strain was able to grow at temperature range from 10 to 30 °C, with an optimum of 25 °C, and growth occurred at pH 6-8. Comparative 16S rRNA gene sequence analysis showed that strain S1-2-1-2-1T belongs to the genus Hymenobacter, with closely related type strains being Hymenobacter daeguensis 16F3Y-2T (95.8% similarity), Hymenobacter rubidus DG7BT (95.8%), Hymenobacter soli PBT (95.7%), Hymenobacter terrenus MIMtkLc17T (95.6%), Hymenobacter terrae DG7AT (95.3%), and Hymenobacter saemangeumensis GSR0100T (95.2%). The genomic DNA G+C content of strain S1-2-1-2-1T was 63.0 mol%. The main polar lipid of this strain was phosphatidylethanolamine, the predominant respiratory quinone was menaquinone-7, and the major fatty acids were C15:0 iso (27.3%), summed feature 3 (C16:1 ω7c/C16:1 ω6c) (16.5%), C15:0 anteiso (15.3%), and C16:0 (14.7%), supporting the affiliation of this strain with the genus Hymenobacter. The results of this polyphasic analysis allowed for the genotypic and phenotypic differentiation of strain S1-2-1-2-1T from recognized Hymenobacter species. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain S1-2-1-2-1T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter agri sp. nov. is proposed. The type strain is S1-2-1-2-1T (=KCTC 52739T = JCM 32194T).

Larkinella terrae sp. nov., isolated from soil on Jeju Island, South Korea.

A Gram-stain negative, non-motile, rod-shaped, aerobic bacterium, designated 15J8-8T, was isolated from a soil sample collected on Jeju Island, South Korea, and characterized taxonomically using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain 15J8-8T belongs to the family Cytophagaceae and is related to Larkinella bovis M2TB15T (95.0%), 'Larkinella harenae' 15J9-9 (94.5%), Larkinella arboricola Z0532T (93.2%), and Larkinella insperata LMG 22510T (93.0%). The DNA G+C content of strain 15J8-8T was 50.5 mol%. The detection of phosphatidylethanolamine and two unidentified polar lipids as major polar lipids; menaquinone-7 as the predominant quinone; and C16:1 ω5c, C16:0 N alcohol, and iso-C15:0 as the major fatty acids also supported the affiliation of the isolate to the genus Larkinella. Based on its phenotypic properties and phylogenetic distinctiveness, strain 15J8-8T should be classified in the genus Larkinella as representative of a novel species, for which the name Larkinella terrae sp. nov. is proposed. The type strain is 15J8-8T (= KCTC 52001T = JCM 31990T).

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

A Gram-stain-negative and orangish yellow-pigmented bacterial strain, designated PR1014KT, was isolated from an automobile evaporator core collected in Korea. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain PR1014KT was related with the members of the genus Spirosoma (94.7-90.2%) and closely related with Spirosoma lacussanchae CPCC 100624T (94.7%), Spirosoma knui 15J8-12T (94.3%), and Spirosoma soli MIMBbqt12T (93.3%). The strain grew at 15-40°C (optimum, 25°C), pH 6.5-7.0 (optimum, 6.5) and 0-1% (w/v) NaCl (optimum, 0%). The predominant fatty acids were summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0, iso-C15:0, C16:1 ω5c, and iso-C17:0 3-OH. The major menaquinone was MK-7. The polar lipid profile of the strain indicated that the presence of one phosphatidylethanolamine, one unidentified aminolipid, two unidentified aminophospholipids, and three unidentified lipids. The DNA G+C content of the strain was 47.4 mol%. On the basis of the phenotypic, genotypic and chemotaxonomic characteristics, strain PR1014KT represents a novel species in the genus Spirosoma, for which the name Spirosoma metallicus sp. nov. (=KACC 17940T =NBRC 110792T) is proposed.

A ß-agarase with high pH stability from Flammeovirga sp. SJP92.

A novel endo-type ß-agarase, AgaB, was cloned from an agar-degrading bacterium, Flammeovirga sp. SJP92. The gene agaB consists of 2, 550 bp and encodes a protein of 849 amino acids including a 19 amino acids signal peptide. Based on the amino acid sequence similarity, AgaB belongs to the glycoside hydrolase family GH16. The recombinant AgaB was expressed in Escherichia coli and exhibited maximal activity at around 45 °C and pH 8.0, with a specific activity of 254.2 U/mg, a Km of 3.99 mg/ml and a Vmax of 700 U/mg for agarose. The agarase was stable at neutral to mildly alkaline condition, and remained 85%-90% of activity after treatment for 1 h, a characteristic much more different from other agarases reported. The recombinant enzyme was sensitive to some metal ions (Cu(2+), Co(2+) and Zn(2+)), but resistant to some denaturants (urea and SDS). It can hydrolyze the ß-1, 4-glycosidic linkages of agarose, yielding neoagarotetraose and neoagarohexaose as the main products. These properties could make AgaB has a potential application in the food, cosmetic and medical industries.

Structure of the O-specific polysaccharide from a marine bacterium Echinicola pacifica КММ 6172(Т) containing 2,3-diacetamido-2,3-dideoxy-D-glucuronic acid.

The O-polysaccharide was isolated from the lipopolysaccharide of Echinicola pacifica KMM 6172(T) and studied by chemical analyses along with (1)H and (13)C NMR spectroscopy, including (1)H, (1)H COSY, 1D and 2D TOCSY, ROESY, (1)H, (13)С HMQC, HMBC and H2BC experiments. It was found that the polysaccharide is built up of branched pentasaccharide repeating units, containing D-galactose (Gal), L-rhamnose (Rha), 2-acetamido-2-deoxy-D-glucose (GlcNAc), two residues of 2,3-diacetamido-2,3-dideoxy-D-glucuronic acid (GlcNAc3NAcA) and O-acetyl group in nonstoichiometric amount and has the following structure [Structure: see text].

Pontibacter locisalis Sy30T sp. nov. isolated from soil collected from an abandoned saltern.

A novel Gram-stain negative, red, rod-shaped, non-motile and aerobic bacterial strain, designated Sy30(T), was isolated from dry soils of an abandoned marine saltern at Weihai, China. 16S rRNA sequence analysis indicated that strain Sy30(T) belongs to the genus Pontibacter in the family Cytophagaceae, with sequence similarities ranging from 93.3 to 96.4 % with other type species of the genus Pontibacter. The predominant cellular fatty acids were iso-C15:0 and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B). The major menaquinone was MK-7. The major polyamine was sym-homospermidine. The DNA G+C content was 47.7 mol%. The major polar lipids consisted of phosphatidylethanolamine, phosphoaminolipid and two unidentified polar lipid. Based on phenotypic, chemotaxonomic and phylogenetic analysis, strain Sy30(T) represents a novel species of the genus Pontibacter in the family Cytophagaceae, phylum Bacteroidetes, for which the name Pontibacter locisalis sp. nov. is proposed. The type strain is Sy30(T) (=KCTC 42498(T) = CICC AB 2015060(T)).

Spirosoma pulveris sp. nov., a bacterium isolated from a dust sample collected at Chungnam province, South Korea.

Strain JSH 5-14(T), a Gram-negative, non-motile, and curved rod-shaped bacterium, was isolated from a dust sample collected at Nonsan, Chungnam province, South Korea, and was characterized to determine its taxonomic position. Phylogenetic analysis based on the 16S rRNA gene sequence of strain JSH 5-14(T) revealed that it belongs to the genus Spirosoma, family Cytophagaceae, class Cytophagia. The highest degree of sequence similarities of strain JSH 5-14(T) were found with Spirosoma liguale DSM 74(T) (97.8%) and Spirosoma endophyticum EX 36(T) (96.2%). The predominant fatty acids were summed feature 3 (composed of C16:1 ω7c/C16:1 ω6c) and C16:1 ω5c. The major polar lipid was phosphatidylethanolamine, and the predominant respiratory quinone was MK-7. Based on the phylogenetic, chemotaxonomic, and phenotypic data, we propose the strain JSH 5-14(T) (=KCTC 42550(T) =JCM 30688(T) =KEMB 9004-165(T)) should be classified as a type strain of a novel species, for which the name Spirosoma pulveris sp. nov., is proposed.

Fibrisoma limi gen. nov., sp. nov., a filamentous bacterium isolated from tidal flats.

An orange-pigmented, Gram-staining-negative, non-motile, filament-forming, rod-shaped bacterium (BUZ 3(T)) was isolated from a coastal mud sample from the North Sea (Fedderwardersiel, Germany) and characterized taxonomically using a polyphasic approach. According to 16S rRNA gene sequence data, it belonged to the family Cytophagaceae, exhibiting low 16S rRNA gene sequence similarity (<90 %) with members of the genera Spirosoma, Rudanella and Fibrella. The DNA G+C content was 52.0 mol%. 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(17 : 0) 3-OH. The major polar lipids consisted of phosphatidylethanolamine and several aminolipids. On the basis of phenotypic, chemotaxonomic and phylogenetic data, it is proposed that strain BUZ 3(T) represents a novel genus and species, for which the name Fibrisoma limi gen. nov., sp. nov. is proposed. The type strain is BUZ 3(T) ( = DSM 22564(T)  = CCUG 58137(T)).

Hymenobacter perfusus sp. nov., Hymenobacter flocculans sp. nov. and Hymenobacter metalli sp. nov. three new species isolated from an uranium mine waste water treatment system.

Three red-pink pigmented strains, designated A1-12(T), A2-50A(T) and A2-91(T), were recovered from two different sites in a uranium mine. For all strains, the optimum growth temperature was 25°C, the optimum pH was 6.0-6.5 and the DNA G+C contents were between 60 and 63.4 mol%. The major respiratory quinone was menaquinone 7 (MK-7) and the fatty acid profiles contained iso- and anteiso-branched C15 fatty acids, summed feature 3 (16:1 ω6c and/or ω7c and/or 15:0 iso 2-OH), summed feature 4 (17:1 anteiso B and/or iso I) and the unsaturated fatty acid 16:1 ω5c as the major components. Phylogenetic analysis of the 16S rRNA gene sequences showed that these organisms represented three distinct branches within the family Flexibacteraceae most closely related to the members of the genus Hymenobacter. Strain A1-12(T) formed a distinct phylogenetic line along with H. rigui KCTC 12533(T) and they shared approximately 98.9% 16S rRNA gene sequence similarity. However, these two strains shared only 14.7% pairwise similarity in their genomic DNA. Strains A2-50A(T) and A2-91(T) formed two distinct lineages, related to the species H. soli KCTC 12607(T), sharing about 95.5% 16S rRNA gene sequence similarity between themselves, and 88.3 and 92.0% with other members of the genus Hymenobacter. Based on the phylogenetic analysis and physiological and biochemical characteristics, these isolates were considered to represent three novel species for which we propose the names Hymenobacter perfusus for strain A1-12(T) (=CIP 110166=LMG 26000), Hymenobacter flocculans for strain A2-50A(T) (=CIP 110139=LMG 25699) and Hymenobacter metalli for strain A2-91(T) (=CIP 110140=LMG 25700).

Adhaeribacter aerophilus sp. nov., Adhaeribacter aerolatus sp. nov. and Segetibacter aerophilus sp. nov., isolated from air samples.

Three bacterial isolates from air samples in Korea, designated strains 6424S-25(T), 6515J-31(T) and 6424S-61(T), were characterized using a polyphasic approach. The cells were strictly aerobic, Gram-stain-negative, non-motile, non-spore-forming and rod-shaped. Phylogenetic analysis of their 16S rRNA gene sequences revealed a clear affiliation with the phylum Bacteroidetes. Strains 6424S-25(T) and 6515J-31(T) showed 16S rRNA gene sequence similarities of 92.7-94.8 % to type strains of recognized species of the genus Adhaeribacter and strain 6424S-61(T) was closely related to Segetibacter koreensis Gsoil 664(T) (93.9 % similarity). The G+C contents of the DNA of strains 6424S-25(T), 6515J-31(T) and 6424S-61(T) were 44.5, 43.9 and 38.4 mol%, respectively. Major fatty acids of strains 6424S-25(T) and 6515J-31(T) were summed feature 4 (iso-C17:1 I and/or anteiso-C17 :1 B), iso-C15:0 and C16:1ω5c. The fatty acid content of strain 6424S-61(T) mainly comprised iso-C15 :1 G and iso-C15:0. Comparative analysis of phenotypic and phylogenetic traits indicated that strains 6424S-25(T) and 6515J-31(T) represented two novel species of the genus Adhaeribacter and that strain 6424S-61(T) should be considered as a novel species of the genus Segetibacter. The names Adhaeribacter aerophilus sp. nov. (type strain 6424S-25(T) =KACC 14118(T) =NBRC 106134(T)), Adhaeribacter aerolatus sp. nov. (type strain 6515J-31(T) =KACC 14117(T) =NBRC 106133(T)) and Segetibacter aerophilus sp. nov. (type strain 6424S-61(T) =KACC 14119(T) =NBRC 106135(T)) are proposed for these organisms.

Role of extracellular polymeric substances in the surface chemical reactivity of Hymenobacter aerophilus, a psychrotolerant bacterium.

Bacterial surface layers, such as extracellular polymeric substances (EPS), are known to play an important role in metal sorption and biomineralization; however, there have been very few studies investigating how environmentally induced changes in EPS production affect the cell's surface chemistry and reactivity. Acid-base titrations, cadmium adsorption assays, and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the surface reactivities of Hymenobacter aerophilus cells with intact EPS (WC) or stripped of EPS (SC) and purified EPS alone. Linear programming modeling of titration data showed SC to possess functional groups corresponding to phosphoryl (pKa approximately 6.5), phosphoryl/amine (pKa approximately 7.9), and amine/hydroxyl (pKa approximately 9.9). EPS and WC both possess carboxyl groups (pKa approximately 5.1 to 5.8) in addition to phosphoryl and amine groups. FT-IR confirmed the presence of polysaccharides and protein in purified EPS that can account for the additional carboxyl groups. An increased ligand density was observed for WC relative to that for SC, leading to an increase in the amount of Cd adsorbed (0.53 to 1.73 mmol/liter per g [dry weight] and 0.53 to 0.59 mmol/liter per g [dry weight], respectively). Overall, the presence of EPS corresponds to an increase in the number and type of functional groups on the surface of H. aerophilus that is reflected by increased metal adsorption relative to that for EPS-free cells.

Hymenobacter tibetensis sp. nov., a UV-resistant bacterium isolated from Qinghai-Tibet plateau.

A brick-red-pigmented strain (XTM003(T)) isolated from the Qinghai-Tibet plateau was investigated using a polyphasic taxonomy approach. Phylogenetic analyses based on 16S rRNA gene sequence indicated that the organism belonged to the genus Hymenobacter. The predominant menaquinone was MK7. The major fatty acids included iso-15:0, 16:1w5c and summed feature 3 (C(16: 1)omega7c and/or C(16: 1)omega6c). The G+C content of the DNA was 55.8%. In addition, DNA-DNA hybridization studies demonstrated that strain XTM003(T) had a relatedness value of 50.7% with the phylogenetically most closely related species Hymenobacter norwichensis DSM 15439(T). Based on the results of phenotypic characteristics and DNA-DNA hybridization studies, strain XTM003(T) is considered to represent a novel species, for which the name Hymenobacter tibetensis sp. nov. is proposed. The type strain is XTM003(T) (=CCTCC AB 207089(T)=NRRL B-51271(T)).

Belliella pelovolcani sp. nov., isolated from a mud-volcano in Taiwan.

Strain CC-SAL-25(T), a non-motile, Gram-negative, red-pigmented bacterium, was isolated from a rare mud-volcano, located in Wandan, Pingtung County, Taiwan. Studies based on 16S rRNA gene sequences showed that the strain clustered closely with Belliella baltica BA143(T) (95.4 % sequence similarity). A menaquinone with seven isoprene units (MK-7) was the major respiratory quinone. The fatty acid profile was slightly different from that of B. baltica BA143(T). The results of the physiological and biochemical tests showed that strain CC-SAL-25(T) could be clearly differentiated from recognized Belliella species based on phenotypic properties. It was evident from the genotypic and phenotypic data that strain CC-SAL-25(T) should be classified as representing a second novel species in the genus Belliella. The name proposed for this taxon is Belliella pelovolcani sp. nov., and the type strain is CC-SAL-25(T) (=BCRC 17883(T)=KCTC 13248(T)).

Flectobacillus roseus sp. nov., isolated from freshwater in Taiwan.

Two Gram-negative, aerobic, pale pink/rose-coloured, rod-shaped, non-motile bacterial strains, designated GFA-11(T) and RG-4, were isolated from a freshwater fish culture pond and a freshwater spring sample, respectively. Based on characterization by using a polyphasic approach, the two strains showed highly similar phenotypic, physiological and genetic characteristics. They shared 99.9 % 16S rRNA gene sequence similarity and 89-94 % DNA-DNA relatedness, suggesting that they represent a single genomic species. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains GFA-11(T) and RG-4 formed a monophyletic branch at the periphery of the evolutionary radiation occupied by the genus Flectobacillus within the family Flexibacteraceae. Their closest neighbours were Flectobacillus major DSM 103(T) (97.7 % 16S rRNA gene sequence similarity) and Flectobacillus lacus CL-GP79(T) (95.9 %). Levels of DNA-DNA relatedness between the two novel strains and the type strains of F. major and F. lacus were less than 70 %. The results of physiological and biochemical tests allowed clear phenotypic differentiation of strains GFA-11(T) and RG-4 from recognized members of the genus Flectobacillus. The predominant fatty acid constituents of strain GFA-11(T) were C(16 : 1)omega5c (40.2 % of the total) and iso-C(15 : 0) (15.0 %). The DNA G+C content of strain GFA-11(T) was 39.7 mol%. On the basis of 16S rRNA gene sequence analysis and chemotaxonomic and physiological data, strains GFA-11(T) and RG-4 are considered to represent a novel species of the genus Flectobacillus, for which the name Flectobacillus roseus sp. nov. is proposed. The type strain is GFA-11(T) (=BCRC 17834(T)=LMG 24501(T)).