Pelistega ratti sp. nov. from Rattus norvegicus of Hainan island

Two strains (NLN63T and NLN82) of Gram-stain-negative, oxidase- and catalase-positive, bacilli-shaped organisms were isolated from the faecal samples of two separate Rattus norvegicus in Baisha county of Hainan Province, Southern PR China. Phylogenetic analysis based on the near full-length 16S rRNA sequences revealed that strain NLN63T belongs to the genus Pelistega , having maximum similarity to Pelistega suis CCUG 64465T (97.1 %), Pelistega europaea CCUG 39967T (96.2 %) and Pelistega indica DSM 27484T (96.2 %), respectively. The phylogenomic tree built on 553 core genes from genomes of 20 species in the genus Pelistega and other adjacent genera further confirmed that strains NLN63T and NLN82 form a distinct subline and exhibit specific phylogenetic affinity with P. europaea CCUG 39967T. In digital DNA–DNA hybridization analyses, strain NLN63T showed low estimated DNA reassociation values (21.4–22.6 %) with the type strains of the species in the genus Pelistega . The DNA G+C contents of strains NLN63T and NLN82 were 37.3 and 37.1 mol%, respectively. Strain NLN63T had a unique MALDI-TOF MS profile, contained Q-8 as the major quinone and C16 : 0, summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c or both) and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c or both) as the dominant fatty acids. Based upon these polyphasic characterization data obtained from the present study, a novel species of the genus Pelistega , Pelistega ratti sp. nov., is proposed with NLN63T (=GDMCC 1.1697T=JCM 33788T) as the type strain.

Success of alignment-free oligonucleotide (k-mer) analysis confirms relative importance of genomes not genes in speciation and phylogeny

The utility of DNA sequence substrings (k-mers) in alignment-free phylogenetic classification, including that of bacteria and viruses, is increasingly recognized. However, its biological basis eludes many 21st century practitioners. A path from the 19th century recognition of the informational basis of heredity to the modern era can be discerned. Crick’s DNA ‘unpairing postulate’ predicted that recombinational pairing of homologous DNAs during meiosis would be mediated by short k-mers in the loops of stem-loop structures extruded from classical duplex helices. The complementary ‘kissing’ duplex loops – like tRNA anticodon–codon k-mer duplexes – would seed a more extensive pairing that would then extend until limited by lack of homology or other factors. Indeed, this became the principle behind alignment-based methods that assessed similarity by degree of DNA–DNA reassociation in vitro. These are now seen as less sensitive than alignment-free methods that are closely consistent, both theoretically and mechanistically, with chromosomal anti-recombination models for the initiation of divergence into new species. The analytical power of k-mer differences supports the theses that evolutionary advance sometimes serves the needs of nucleic acids (genomes) rather than proteins (genes), and that such differences can play a role in early speciation events.

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 12531T as its closest neighbour (97.8 % sequence similarity). Comparative genome analysis of two representative strains (i.e. R-68523T 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. C16 : 1 ω7c and/or iso-C15 2-OH), C16 : 1 ω5c, C16 : 0 and iso-C15 : 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-68523T (=LMG 31447T=CECT 9925T).

Leucobacter zeae sp. nov., isolated from the rhizosphere of maize (Zea mays L.)

A novel yellow-pigmented, aerobic, rod-shaped, non-motile bacterium, designated strain CC-MF41T, was isolated from rhizosphere soil of maize (Zea mays) collected in Wufeng District, Taichung, Taiwan. Strain CC-MF41T exhibited 16S rRNA gene sequence similarity of 97.5, 97.3, 97.2 and 97.1 % to Leucobacter chironomi MM2LBT (and ‘Leucobacter kyeonggiensis’ F3-P9 and ‘L. humi’ Re-6, the names of which have not been validly published), Leucobacter tardus K70/01T, L. komagatae IFO 15245T and ‘Leucobacter margaritiformis’ A23. However, CC-MF41T and ‘L. margaritiformis’ A23 formed a loosely bound phylogenetic lineage (with a low bootstrap value) associated with species of the genus Leucobacter. In DNA–DNA reassociation experiments, the relatedness of strain CC-MF41T to L. chironomi DSM 19883T was 57.1 % (reciprocal value 29.1 %). The DNA G+C content of strain CC-MF41T was 72.1 mol% and the cell-wall peptidoglycan contained 2,4-diaminobutyric acid, alanine, glycine, glutamic acid and threonine. The major menaquinone was MK-11 and the predominant fatty acids were iso-C16 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. The polar lipid profile of strain CC-MF41T contained major amounts of diphosphatidylglycerol followed by an unidentified glycolipid, phosphatidylglycerol and an unknown phospholipid. Based on its phylogenetic, phenotypic and chemotaxonomic distinctiveness, strain CC-MF41T represents a novel species of Leucobacter, for which the name Leucobacter zeae sp. nov. is proposed. The type strain is CC-MF41T ( = BCRC 80515T = LMG 27265T).

Ornithinimicrobium algicola sp. nov., a marine actinobacterium isolated from the green alga of the genus Ulva

A Gram-staining-positive, non-spore-forming actinobacterium, strain JC311T, isolated from marine green alga of the genus Ulva was studied to examine its taxonomic position. On the basis of the 16S rRNA gene sequence similarity studies, strain JC311T was shown represent a member of the genus Ornithinimicrobium and to be closely related to Ornithinimicrobium pekingense LW6T (98.6 %), Ornithinimicrobium kibberense K22-20T (98.3 %) and Ornithinimicrobium humiphilum HKI 0124T (98.1 %). However, strain JC311T showed less than 22 % DNA reassociation value (based on DNA–DNA hybridization) with O. pekingense JCM14001T, O. kibberense JCM12763T and O. humiphilum KCTC19901T. The predominant menaquinone of strain JC311T was MK-8(H4). The peptidoglycan contained l-ornithine as the diagnostic diamino acid. The polar lipid profile consisted of the lipids diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, glycophospholipid, aminophospholipid, phospholipid and two unidentified lipids. The major fatty acids iso-C16 : 0, iso-C15 : 0, iso-C17 : 1ω9c and iso-C17 : 0 were consistent with the fatty acid patterns reported for members of the genus Ornithinimicrobium. The distinct genomic, morphological, physiological and chemotaxonomic differences from the previously described taxa support the classification of JC311T as a representative of a novel species of the genus Ornithinimicrobium, for which we propose the name Ornithinimicrobium algicola sp. nov., with the type strain JC311T ( = KCTC 39559 T = LMG 28808T).

Pseudoclavibacter terrae sp. nov. isolated from rhizosphere soil of Ophiopogon japonicus

Strain THG-MD12T, a Gram-reaction-positive, aerobic, non-motile, rod-shaped bacterium was isolated from rhizosphere soil of Ophiopogon japonicus in PR China. THG-MD12T was closely related to members of the genus Pseudoclavibacter and showed the highest 16S rRNA gene sequence similarities with Pseudoclavibacter helvolus KCTC 19531T (98.8 %) and Pseudoclavibacter chungangensis KCTC 22691T (96.9 %). DNA–DNA hybridization showed 41.9 ± 2.1 % and 12.4 ± 0.9 % DNA reassociation with P. helvolus KCTC 19531T and P. chungangensis KCTC 22691T, respectively. Chemotaxonomic analyses revealed that strain THG-MD12T possesses menaquinone-9 as the predominant respiratory quinone, 2,4-diaminobutyric acid as the diamino acid in the peptidoglycan and anteiso-C15 : 0, iso-C16 : 0, C16 : 0 and anteiso-C17 : 0 as the major fatty acids. The polar lipid profile was found to consist of diphosphatidylglycerol, phosphatidylglycerol, two unknown glycolipids and two unknown lipids. These data corroborated the affiliation of THG-MD12T to the genus Pseudoclavibacter. Thus, the isolate represents a novel species, for which the name Pseudoclavibacter terrae sp. nov. is proposed, with THG-MD12T as the type strain ( = CCTCC AB 2015124T = KCTC 39562T).

Epilithonimonas psychrotolerans sp. nov., isolated from alpine permafrost

A bacterial strain, designated TSBY 57T, was isolated during a study on the phylogenetic diversity of culturable bacteria from alpine permafrost in Tianshan Mountains, China, and was classified by means of a polyphasic taxonomic approach. The novel strain was found to belong to the genus Epilithonimonas and was distinguished from recognized species of this genus. Strain TSBY 57T grew aerobically, at 0–30 °C, with 0–1.5 % (w/v) NaCl and at pH 6–8.Cells were Gram-stain-negative, non-motile, non-spore-forming rods. Compared with the reference strains, the novel strain was psychrotolerant. The predominant fatty acids were summed feature 3 (consisting of C16 : 1ω7c and/or C16 : 1ω6c), anteiso-C15 : 0 and iso-C15 : 0.The sole respiratory quinone was MK-6.Phosphatidylethanolamine was predominant in the polar lipid profile of strain TSBY 57T. These chemotaxonomic traits were in good agreement with the characteristics of the genus Epilithonimonas. On the basis of 16S rRNA gene sequence similarity, strain TSBY 57T was a member of the genus Epilithonimonas and was closely related to Epilithonimonas tenax DSM 16811T (99.0 %), Epilithonimonas ginsengisoli DCY78T (98.6 %) and Epilithonimonas lactis H1T (98.5 %). However, DNA–DNA reassociation values between strain TSBY 57T and E. tenax DSM 16811T, E. ginsengisoli DCY78T and E. lactis H1T were 39.5 ± 2.6, 37.7 ± 1.0 and 37.3 ± 1.1 %, respectively. The G+C content of the DNA was 34.4 ± 0.2 mol%. Based on data from this polyphasic taxonomic study, strain TSBY 57T represents a novel species of the genus Epilithonimonas, for which the name Epilithonimonas psychrotolerans sp. nov. is proposed. The type strain is TSBY 57T ( = NRRL B-51307T = CCTCC AB 207182T).

Multilocus sequence analysis of the genus Kurthia, and a description of Kurthia populi sp. nov.

Four novel bacterial strains belonging to the genus Kurthia were isolated from the surface of a weevil of the family Curculionidae (strain 10y-14T), and from bark samples of hybrid poplar, Populus × euramericana (strains 6-3, 2-5 and 06C10-3-14), in Puyang, Henan Province, China. Phylogenetic analyses of the 16S rRNA gene and multilocus sequence analysis (MLSA) data showed that the four strains form a distinct cluster in the genus Kurthia, indicating that they all belong to a single taxon within the genus. DNA–DNA hybridization levels between strain 10y-4T and Kurthia huakuii LAM0618T and Kurthia massiliensis DSM 24639T were 58.31 and 53.92 %, respectively. This indicates that the four novel strains represent a species distinct from these two closely related species. The DNA G+C content of the novel strains was 42.1–42.6 %. The major fatty acids were iso-C15 : 0 and anteiso-C15 : 0.The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unknown phospholipid and unidentified aminophospholipids. The predominant menaquinones were MK-7 (90 %) and MK-6 (10 %). The major cell-wall amino acids were lysine, alanine, glutamic acid and glycine. On the basis of the MLSA and 16S rRNA gene sequence phylogenetic analyses, DNA–DNA reassociation values, DNA base composition, and biochemical and phenotypic characteristics, the four strains are considered to represent a novel species within the genus Kurthia, for which the name Kurthia populi sp. nov. is proposed. The type strain is 10y-14T ( = CFCC 11600T = KCTC 33522T).

Sphingobacterium mucilaginosum sp. nov., isolated from rhizosphere soil of a rose

A Gram-stain-negative, strictly aerobic, motile, short-rod-shaped bacterium, designated strain THG-SQA8T, was isolated from rhizosphere soil of rose in PR China. Strain THG-SQA8T was closely related to members of the genus Sphingobacterium, showed the highest sequence similarities with Sphingobacterium multivorum KACC 14105T (98.0 %) and Sphingobacterium ginsenosidimutans KACC 14526T (97.4 %). DNA–DNA hybridization showed values of 35.2 ± 0.9 % and 8.8 ± 0.3 % DNA reassociation with S. multivorum KACC 14105T and S. ginsenosidimutans KACC 14526T, respectively. Chemotaxonomic data revealed that strain THG-SQA8T possesses menaquinone-7 as the only respiratory quinone, and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 and C16 : 0 as the major fatty acids. The major polar lipid was phosphatidylethanolamine. The DNA G+C content was 40.7 mol%. These data corroborated the affiliation of strain THG-SQA8T to the genus Sphingobacterium. Thus, the isolate represents a novel species, for which the name Sphingobacterium mucilaginosum sp. nov. is proposed, with THG-SQA8T as the type strain ( = CCTCC AB 2014317T = KCTC 42503T).