Roseococcus microcysteis sp. nov., isolated from a Microcystis aeruginosa culture sample

Strain NIBR12T (=KACC 22094T=HAMBI 3739T), a novel Gram-stain-negative, obligate aerobic, non-spore-forming, non-motile and coccobacillus-shaped bacterium, was isolated from a cyanobacterial sample culture (Microcysitis aeruginosa NIBRCYC000000452). The newly identified bacterial strain grew optimally in modified Reasoner's 2A medium under the following conditions: 0 % (w/v) NaCl, pH 7.5 and 35 °C. Phylogenetic analysis using the 16S rRNA gene sequence confirmed that strain NIBR12T belongs to the genus Roseococcus , with its closest neighbours being Roseococcus suduntuyensis SHETT (98.8%), Roseococcus thiosulfatophilus RB-3T (97.7%), “Sediminicoccus rosea” R-30T (95.7 %) and Rubritepida flocculans H-8T (95.0 %). Genomic comparison of strain NIBR12T with type species in the genus Roseococcus was conducted using digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity analyses, resulting in values of ≤53.7, ≤93.7 and ≤96.1 %, respectively. The genomic DNA G+C content of strain NIBR12T was 70.9 mol%. The major fatty acids of strain NIBR12T were summed feature 8 (C18 : 1 ω7c and/or C18:1 ω6c) and summed feature 3 (C16 : 1 ω6c/C16 : 1 ω7c). Q-9 was its major respiratory quinone. Moreover, the major polar lipids of strain NIBR12T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. Based on our chemotaxonomic, genotypic and phenotype analyses, strain NIBR12T is identified as represeting a novel species of the genus Roseococcus , for which the name Roseococcus microcysteis sp. nov. is proposed.

Aliarcobacter, Halarcobacter, Malaciobacter, Pseudarcobacter and Poseidonibacter are later synonyms of Arcobacter: transfer of Poseidonibacter parvus, Poseidonibacter antarcticus, ‘Halarcobacter arenosus’, and ‘Aliarcobacter vitoriensis’ to Arcobacter as Arcobacter parvus comb. nov., Arcobacter antarcticus comb. nov., Arcobacter arenosus comb. nov. and Arcobacter vitoriensis comb. nov.

This paper re-examines the taxonomic positions of recently described Poseidonibacter (P. parvum and P. antarcticus ), Aliarcobacter (‘Al. vitoriensis’), Halarcobacter (‘H. arenosus’) and Arcobacter ( A. caeni , A. lacus ) species, and other species proposed to represent novel genera highly related to the genus Arcobacter . Phylogenomic and several overall genome relatedness indices (OGRIs) were applied to a total of 118 representative genomes for this purpose. Phylogenomic analyses demonstrated the Arcobacter clade to be distinct from other Epsilonproteobacteria , clearly defined and containing closely related species. Aliarcobacter butzleri and Malaciobacter pacificus did not cluster with other members of these proposed genera, indicating incoherence of these genera. Every OGRI measure applied indicated a high level of relatedness among all Arcobacter clade species, including the recently described taxa studied here, and substantially lower between type species representatives for other Epsilonproteobacteria. Where published guidelines were available, OGRI values for Arcobacter clade species were either unsupportive of division into other genera or were at the lowest boundary range (for average amino acid identity). We propose that Aliarcobacter , Halarcobacter , Malaciobacter , Pseudarcobacter , Poseidonibacter and Arcobacter sensu stricto be considered members of a single genus, Arcobacter , and subsequently transfer P. parvum, P. antarcticus , ‘ Al. vitoriensis ’ and ‘H. arenosus’ to Arcobacter as Arcobacter parvum comb. nov., Arcobacter antarcticus comb. nov., Arcobacter vitoriensis comb. nov. and Arcobacter arenosus comb. nov.

Limnovirga soli gen. nov., sp. nov., isolated from river sediment

A cream-coloured, Gram-stain-negative, rod-shaped bacterium, designated strain KSC-6T, was isolated from soil sampled at the Gapcheon River watershed in Daejeon, Republic of Korea. The organism does not require NaCl for growth and grows at pH 6.0–8.0 (optimum, pH 7.0) and 10–37 °C (optimum, 25 °C). Phylogenetic trees based on the 16S rRNA gene sequences reveal that strain KSC-6T belongs to the family Chitinophagaceae within the order Chitinophagales and is most closely related to Panacibacter ginsenosidivorans Gsoil 1550T (95.9% similarity). The genomic DNA G+C content was 38.9 mol%. The major cellular fatty acids (>8 %) of strain KCS-6T were iso-C15:0, iso-C15 : 1 G and iso-C17 : 0 3-OH. The predominant respiratory quinone was menaquinone 7 and the predominant polar lipids were phosphatidylethanolamine, five unidentified aminolipids and two unidentified lipids. Based on genome analyses, low digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity values with closely related genera, and differential chemotaxonomic and physiological properties, we suggest that strain KCS-6T represents a novel species in a new genus in the family Chitinophagaceae , for which the name Limnovirga soli gen. nov., sp. nov. (type strain KCS-6T=KCCM 43337T=NBRC 114336T) is proposed.

Aquariibacter albus gen. nov., sp. nov., a new member of the order Burkholderiales, isolated from a freshwater aquarium

A novel bacterium, strain SJAQ100T, was isolated from a freshwater aquarium and was characterized taxonomically and phylogenetically. Strain SJAQ100T was a Gram-stain-negative, aerobic, rod-shaped and non-motile bacterium. The strain grew optimally with 0 % NaCl and at 25–37 °C on Reasoner's 2A agar. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the strain SJAQ100T clustered with members of Burkholderiales incertae sedis in the order Burkholderiales , but sequence similarities to known species were less than 96.5 %. The genomic DNA G+C content of strain SJAQ100T was 71.2 mol%. Genomic comparisons of strain SJAQ100T with species in the order Burkholderiales were made using the Genome-to-Genome Distance Calculator, average nucleotide identity and average amino acid identity analyses (values indicated ≤22.1, ≤78.1, and ≤68.1 % respectively). Strain SJAQ100T contained C16 : 0 and C16 : 1 ω7c/C16 : 1 ω6c as major fatty acids and Q-8 as the major quinone. The major polyamines were putrescine and cadaverine. Strain SJAQ100T contained phosphatidylethanolamine and diphosphatidylglycerol as major polar lipids. Based on the genotypic, chemotaxonomic and phenotypic results, strain SJAQ100T represents a novel genus and species, Aquariibacter albus gen. nov., sp. nov., which belongs to order Burkholderiales and the class Betaproteobacteria . The type strain is SJAQ100T (=KCTC 72203T=CGMCC 1.18869T=MCC 4385T).

Genome-Based Taxonomic Rearrangement of the Order Geobacterales Including the Description of Geomonas azotofigens sp. nov. and Geomonas diazotrophica sp. nov.

Geobacterales is a recently proposed order comprising members who originally belonged to the well-known family Geobacteraceae, which is a key group in terrestrial ecosystems involved in biogeochemical cycles and has been widely investigated in bioelectrochemistry and bioenergy fields. Previous studies have illustrated the taxonomic structure of most members in this group based on genomic phylogeny; however, several members are still in a pendent or chaotic taxonomic status owing to the lack of genome sequences. To address this issue, we performed this taxonomic reassignment using currently available genome sequences, along with the description of two novel paddy soil-isolated strains, designated Red51T and Red69T, which are phylogenetically located within this order. Phylogenomic analysis based on 120 ubiquitous single-copy proteins robustly separated the species Geobacter luticola from other known genera and placed the genus Oryzomonas (fam. Geobacteraceae) into the family ‘Pseudopelobacteraceae’; thus, a novel genus Geomobilimonas is proposed, and the family ‘Pseudopelobacteraceae’ was emended. Moreover, genomic comparisons with similarity indexes, including average amino acid identity (AAI), percentage of conserved protein (POCP), and average nucleotide identity (ANI), showed proper thresholds as genera boundaries in this order with values of 70%, 65%, and 74% for AAI, POCP, and ANI, respectively. Based on this, the three species Geobacter argillaceus, Geobacter pelophilus, and Geobacter chapellei should be three novel genera, for which the names Geomobilibacter, Geoanaerobacter, and Pelotalea are proposed, respectively. In addition, the two novel isolated strains phylogenetically belonged to the genus Geomonas, family Geobacteraceae, and shared genomic similarity values higher than those of genera boundaries, but lower than those of species boundaries with each other and their neighbors. Taken together with phenotypic and chemotaxonomic characteristics similar to other Geomonas species, these two strains, Red51T and Red69T, represent two novel species in the genus Geomonas, for which the names Geomonas azotofigens sp. nov. and Geomonas diazotrophica sp. nov. are proposed, respectively.

Fibrivirga Algicola Gen. Nov., Sp. Nov., An Algicidal Bacterium Isolated from a Freshwater River

An aerobic, gram-negative, pink-colored, non-motile, rod-shaped algicidal bacterium, designated JA-25T was isolated from the freshwater of the Geumgang River, Republic of Korea. It grew at 15–30°C, 6.0–9.0 pH, and in the presence of 0–1% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JA-25T belongs to the Family ‘Spirosomaceae’ and is most closely related to Fibrella aestuarina BUZ 2T (93.6%). The strain JA-25T showed < 90% sequence similarity to other members of the Family ‘Spirosomaceae’. The average nucleotide identity(ANI), in silico DNA-DNA hybridization and the average amino acid identity(AAI) values based on the genomic sequences of JA-25T and F. aestuarina BUZ 2T were 74.4, 20.5 and 73.6 %, respectively. The genomic DNA G + C content was 52.5mol %. The major cellular fatty acids were Summed feature 3 (C16:1 ω6c/C16:1 ω7c), C16:1 ω5c, C16:0 (> 10%). The genomic DNA G + C content was 52.5 mol %. The major respiratory quinone was MK-7 and the polar lipids were phosphatidylethanolamine, two unidentified aminolipids, two phospholipids and five unidentified lipids. Considering the phylogenetic inference, phenotypic and chemotaxonomic data, strain JA-25T should be classified as a novel species of the novel genus Fibrivirga, with the proposed name Fibrivirga algicola sp. nov. The type strain is JA-25T (= KCCM 43334T = NBRC 114259T).

Characterization of Martelella soudanensis sp. nov., Isolated from a Mine Sediment

Gram-stain-negative, strictly aerobic, non-spore-forming, non-motile, and rod-shaped bacterial strains, designated NC18T and NC20, were isolated from the sediment near-vertical borehole effluent originating 714 m below the subsurface located in the Soudan Iron Mine in Minnesota, USA. The 16S rRNA gene sequence showed that strains NC18T and NC20 grouped with members of the genus Martelella, including M. mediterranea DSM 17316T and M. limonii YC7034T. The genome sizes and G + C content of both NC18T and NC20 were 6.1 Mb and 61.8 mol%, respectively. Average nucleotide identity (ANI), the average amino acid identity (AAI), and digital DNA–DNA hybridization (dDDH) values were below the species delineation threshold. Pan-genomic analysis showed that NC18T, NC20, M. mediterranea DSM 17316T, M. endophytica YC6887T, and M. lutilitoris GH2-6T had 8470 pan-genome orthologous groups (POGs) in total. Five Martelella strains shared 2258 POG core, which were mainly associated with amino acid transport and metabolism, general function prediction only, carbohydrate transport and metabolism, translation, ribosomal structure and biogenesis, and transcription. The two novel strains had major fatty acids (>5%) including summed feature 8 (C18:1 ω7c and/or C18:1 ω6c), C19:0 cyclo ω8c, C16:0, C18:1 ω7c 11-methyl, C18:0, and summed feature 2 (C12:0 aldehyde and/or iso-C16:1 I and/or C14:0 3-OH). The sole respiratory quinone was uniquinone-10 (Q-10). On the basis of polyphasic taxonomic analyses, strains NC18T and NC20 represent novel species of the genus Martelella, for which the name Martelella soudanensis sp. nov. is proposed. The type strain is NC18T (=KTCT 82174T = NBRC 114661T).

Phylotaxogenomics for the Reappraisal of the Genus Roseomonas With the Creation of Six New Genera

The genus Roseomonas is a significant group of bacteria which is invariably of great clinical and ecological importance. Previous studies have shown that the genus Roseomonas is polyphyletic in nature. Our present study focused on generating a lucid understanding of the phylogenetic framework for the re-evaluation and reclassification of the genus Roseomonas. Phylogenetic studies based on the 16S rRNA gene and 92 concatenated genes suggested that the genus is heterogeneous, forming seven major groups. Existing Roseomonas species were subjected to an array of genomic, phenotypic, and chemotaxonomic analyses in order to resolve the heterogeneity. Genomic similarity indices (dDDH and ANI) indicated that the members were well-defined at the species level. The Percentage of Conserved Proteins (POCP) and the average Amino Acid Identity (AAI) values between the groups of the genus Roseomonas and other interspersing members of the family Acetobacteraceae were below 65 and 70%, respectively. The pan-genome evaluation depicted that the pan-genome was an open type and the members shared 958 core genes. This claim of reclassification was equally supported by the phenotypic and chemotaxonomic differences between the groups. Thus, in this study, we propose to re-evaluate and reclassify the genus Roseomonas and propose six novel genera as Pararoseomonas gen. nov., Falsiroseomonas gen. nov., Paeniroseomonas gen. nov., Plastoroseomonas gen. nov., Neoroseomonas gen. nov., and Pseudoroseomonas gen. nov.

Taxonomy of Rhizobiaceae revisited: proposal of a new framework for genus delimitation

The alphaproteobacterial family Rhizobiaceae is highly diverse, with 168 species with validly published names classified into 17 genera with validly published names. Most named genera in this family are delineated based on genomic relatedness and phylogenetic relationships, but some historically named genera show inconsistent distribution and phylogenetic breadth. Most problematic is Rhizobium, which is notorious for being highly paraphyletic, as most newly described species in the family being assigned to this genus without consideration for their proximity to existing genera, or the need to create novel genera. In addition, many Rhizobiaceae genera lack synapomorphic traits that would give them biological and ecological significance. We propose a common framework for genus delimitation within the family Rhizobiaceae. We propose that genera in this family should be defined as monophyletic groups in a core-genome gene phylogeny, that are separated from related species using a pairwise core-proteome average amino acid identity (cpAAI) threshold of approximately 86%. We further propose that the presence of additional genomic or phenotypic evidence can justify the division of species into separate genera even if they all share greater than 86% cpAAI. Applying this framework, we propose to reclassify Rhizobium rhizosphaerae and Rhizobium oryzae into the new genus Xaviernesmea gen. nov. Data is also provided to support the recently proposed genus "Peteryoungia", and the reclassifications of Rhizobium yantingense as Endobacterium yantingense comb. nov., Rhizobium petrolearium as Neorhizobium petrolearium comb. nov., Rhizobium arenae as Pararhizobium arenae comb. nov., Rhizobium tarimense as Pseudorhizobium tarimense comb. nov., and Rhizobium azooxidefex as Mycoplana azooxidifex comb. nov. Lastly, we present arguments that the unification of the genera Ensifer and Sinorhizobium in Opinion 84 of the Judicial Commission is no longer justified by current genomic and phenotypic data. We thus argue that the genus Sinorhizobium is not illegitimate and now encompasses 17 species.

Sphingomonas sabuli sp. nov., a carotenoid-producing bacterium isolated from beach sand

A Gram-stain-negative, aerobic and non-motile bacterium, strain sand1-3T, was isolated from beach sand collected from Haeundae Beach located in Busan, Republic of Korea. Based on the results of 16S rRNA gene sequence and phylogenetic analyses, Sphingomonas daechungensis CH15-11T (97.0 %), Sphingomonas edaphi DAC4T (96.8 %), Sphingomonas xanthus AE3T (96.5 %) and Sphingomonas oryziterrae YC6722T (96.0 %) were selected for comparing phenotypic and chemotaxonomic characteristics. Cells of strain sand1-3T grew at 7–50 °C (optimum, 30–35 °C), pH 5.0–8.0 (optimum, pH 7.0–8.0) and in the presence of 0–0.5 % (w/v) NaCl (optimum, 0 %). Major polar lipids included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, sphingoglycolipid, one unidentified glycolipid and one unidentified phosphoglycolipid. The major fatty acids were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c) and C18 : 1 2-OH. Moreover, the sole respiratory quinone and major polyamine were identified as ubiquinone-10 and homospermidine, respectively. The genomic DNA G+C content was 65.9 mol%. The digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity values of strain sand1-3T and its reference strains with publicly available genomes were 17.9–18.9 %, 72.0–75.3 % and 63.3–76.5 % respectively. Based on polyphasic evidence, we propose Sphingomonas sabuli sp. nov. as a novel species within the genus Sphingomonas . The type strain is sand1-3T (=KCTC 82358T=NBRC 114538T).