Description of a new freshwater bacterium Aquirufa regiilacus sp. nov., classification of the genera Aquirufa, Arundinibacter, Sandaracinomonas, and Tellurirhabdus to the family Spirosomataceae, classification of the genus Chryseotalea to the family Fulvivirgaceae and Litoribacter to the family Cyclobacteriaceae, as well as classification of Litoribacter alkaliphilus as a later heterotypic synonym of Litoribacter ruber.

Strains LEOWEIH-7CT and LEPPI-3A were isolated from the Leopoldskroner Weiher, a lake located in the city of Salzburg, Austria. 16S rRNA gene similarities and phylogenetic reconstructions with 16S rRNA gene sequences as well as based on genome sequences revealed that the new strains belong to the A. antheringensis branch of the genus Aquirufa. Calculated whole-genome average nucleotide identity (gANI) and digital DNA-DNA hybridization (dDDH) values with the closely related type strains showed that the two strains represent a single new species. The strains grew aerobically and chemoorganotrophically, and the cells were rod shaped, on average 0.8 µm long and 0.3 µm wide, red pigmented and motile by gliding. The genome size of both strains was 2.6 Mbp and the G+C value was 41.9%. The genomes comprised genes predicted for the complete light-harvesting rhodopsin system and various carotenoids. We proposed to establish the name Aquirufa regiilacus sp. nov. for strain LEOWEIH-7CT (=DSM 116390T = JCM 36347T) as the type strain. Strain LEPPI-3A (=DSM 116391 = JCM 36348) also belongs to this new species. The calculated genome-based phylogenetic tree revealed that Aquirufa and some other genera currently allocated in the family Cytophagaceae need a reclassification. Aquirufa, Arundinibacter, Sandaracinomonas, and Tellurirhabdus should be designated to the family Spirosomataceae, the genus Chryseotalea to the family Fulvivirgaceae, and the genus Litoribacter to the family Cyclobacteriaceae. Furthermore, based on calculated gANI and dDDH values, Litoribacter alkaliphilus should be reclassified as a later heterotypic synonym of Litoribacter ruber.

Arcicella gelida sp. nov. and Arcicella lustrica sp. nov., isolated from streams in China and re-examining the taxonomic status of all the genera within the families Spirosomataceae and Cytophagaceae.

Three Gram-stain-negative, aerobic, rod-shaped, non-motile strains (DC2WT, DC25WT, and LKC2W) were isolated from streams in China. Comparisons based on the 16S rRNA gene sequences showed that these three strains share 16S rRNA gene sequence similarity values over 97.0 % with the species of genus Arcicella. There was confusion due to the fact that all species of genera Flectobacillus, Aquirufa, and Sandaracinomonas show 16S rRNA gene sequence similarity of over 90.0 % to the above three strains, but the genus Flectobacillus belongs to the family Spirosomataceae and the genera Aquirufa and Sandaracinomonas belong to the family Cytophagaceae. Observing the phylogenetic trees, strains DC2WT, DC25WT, and LKC2W cluster closely with the species of genus Arcicella, but some species within the families Spirosomataceae and Cytophagaceae are not monophyletic. The phylogenomic tree also showed a confused phylogenetic relationships among these non-monophyletic species. Combining the phylogenetic relationships and average nucleotide identity values, the current taxonomic status of all the genera within the families Spirosomataceae and Cytophagaceae were re-examined. The genera 'Chryseosolibacter', 'Dawidia', and Chryseotalea should belong to the new family Chryseotaleaceae fam. nov., the genera Arcicella, Flectobacillus, Pseudarcicella, Aquirufa, and Sandaracinomonas should belong to the new family Flectobacillaceae fam. nov., the genera Fluviimonas, Taeseokella, Arcticibacterium, Emticicia, Jiulongibacter, Marinilongibacter, Lacihabitans, and Leadbetterella should belong to the new family Leadbetterellaceae fam. nov., the genus Litoribacter should be reassigned to the family Cyclobacteriaceae, and the genera Arundinibacter and Tellurirhabdus should be reassigned to the family Spirosomataceae. Strains DC2WT and DC25WT are reported to represent two novel species of the genus Arcicella, for which the names Arcicella gelida sp. nov. (type strain DC2WT=GDMCC 1.3209T=KCTC 92559T) and Arcicella lustrica sp. nov. (type strain DC25WT=GDMCC 1.3210T=KCTC 92557T) are proposed.

Identification and evolution of non-traditional nitrilase from Spirosoma linguale DSM 74 with high hydration activity.

Hydration, a secondary activity mediated by nitrilase, is a promising new pathway for amide production. However, low hydration activity of nitrilase or trade-off between hydration and catalytic activity hinders its application in the production of amides. Here, natural C-terminal-truncated wild-type nitrilase, mined from a public database, obtained a high-hydration activity nitrilase as a novel evolutionary starting point for further protein engineering. The nitrilase Nit-74 from Spirosoma linguale DSM 74 was successfully obtained and exhibited the highest hydration activity level, performing 50.7 % nicotinamide formation and 87.6 % conversion to 2 mM substrate 3-cyanopyridine. Steric hindrance of the catalytic activity center and the N-terminus of the catalytic cysteine residue helped us identify three key residues: I166, W168, and T191. Saturation mutations resulted in three single mutants that further improved the hydration activity of N-heterocyclic nitriles. Among them, the mutant T191S performed 72.7 % nicotinamide formation, which was much higher than the previously reported highest level of 18.7 %. Additionally, mutants I166N and W168Y exhibited a 97.5 % 2-picolinamide ratio and 97.7 % isonicotinamide ratio without any loss of catalytic activity, which did not indicate a trade-off effect. Our results expand the screening and evolution library of promiscuous nitrilases with high hydration activity for amide formation.

Dyadobacter chenhuakuii sp. nov., Dyadobacter chenwenxiniae sp. nov., and Dyadobacter fanqingshengii sp. nov., isolated from soil of the Qinghai-Tibetan Plateau.

Six novel bacterial strains, designated CY22T, CY357, LJ419T, LJ53, CY399T and CY107 were isolated from soil samples collected from the Qinghai-Tibetan Plateau, PR China. Cells were aerobic, rod-shaped, yellow-pigmented, catalase- and oxidase-positive, Gram-stain-negative, non-motile and non-spore-forming. All strains were psychrotolerant and could grow at 0 °C. The results of phylogenetic and phylogenomic analyses, based on 16S rRNA gene sequences and core genomic genes, indicated that the three strain pairs (CY22T/CY357, LJ419T/LJ53 and CY399T/CY107) were closely related to members of the genus Dyadobacter and clustered tightly with two species with validly published names, Dyadobacter alkalitolerans 12116T and Dyadobacter psychrophilus BZ26T. Values of digital DNA-DNA hybridization between genome sequences of the isolates and other strains from the GenBank database in the genus Dyadobacter were far below the 70.0 % threshold. The genomic DNA G+C content of these six strains ranged from 45.2 to 45.8 %. The major cellular fatty acids of all six strains were iso-C15 : 0 and summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c). MK-7 was the only respiratory quinone, and phosphatidylethanolamine was the predominant polar lipid for strains CY22T, LJ419T and CY399T. On the basis of the phenotypic, phylogenetic and genomic evidence presented, these six strains represent three novel members of the genus Dyadobacter, for which the names Dyadobacter chenhuakuii sp. nov., Dyadobacter chenwenxiniae sp. nov. and Dyadobacter fanqingshengii sp. nov. are proposed. The type strains are CY22T (= GDMCC 1.3045T = KCTC 92299T), LJ419T (= GDMCC 1.2872T = JCM 33794T) and CY399T (= GDMCC 1.3052T = KCTC 92306T), respectively.

Pontibacter liquoris sp. nov. and Pontibacter vulgaris sp. nov., two novel bacteria isolated from the pit mud of Chinese liquor.

Two pink-pigmented bacterial strains, designated NBU2971T and NBU2972T, were isolated from the pit mud of a Chinese liquor. Phylogenetic analyses based on 16S rRNA gene sequences suggested that strains NBU2971T and NBU2972T formed a distinct lineage within the family Hymenobacteraceae and were closely related to members of the genus Pontibacter. 16S rRNA gene sequences revealed that strain NBU2971T showed highest similarity of 97.9 % to Pontibacter arcticus 2b14T, and strain NBU2972T showed the highest similarity of 96.9 % to Pontibacter deserti JC215T. The 16S rRNA gene sequence similarity, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two novel strains were 95.2, 73.8 and 19.6 %, respectively, suggesting that they represent different species. The ANI and dDDH values between two novel strains and related species of genus Pontibacter were well below the threshold limit for prokaryotic species delineation. The genomic DNA G+C contents of strains NBU2971T and NBU2972T were 51.3 and 44.5 mol%, respectively. The major cellular fatty acids of the two novel strains were iso-C15 : 0 and summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B). The major polar lipid of both novel strains was phosphatidylethanolamine. The only respiratory quinone was MK-7. Combining results of phenotypic, chemotaxonomic and genotypic data, strains NBU2971T and NBU2972T are considered to be two representatives in the genus Pontibacter, which the name Pontibacter liquoris sp. nov. and Pontibacter vulgaris sp. nov. are proposed. The type strains of the new species are NBU2971T (=KCTC 82916T=MCCC 1K06395T) and NBU2972T (=KCTC 82917T=MCCC 1K06396T), respectively.

Five novel Hymenobacter species isolated from air: Hymenobacter cellulosilyticus sp. nov., Hymenobacter cellulosivorans sp. nov., Hymenobacter aerilatus sp. nov., Hymenobacter sublimis sp. nov. and Hymenobacter volaticus sp. nov.

Five Hymenobacter strains isolated from air samples collected from the Suwon and Jeju regions of the Republic of Korea were studied using polyphasic taxonomic methods. Using 16S rRNA gene sequences and the resulting phylogenetic tree, the strains were primarily identified as members of the genus Hymenobacter. Digital DNA-DNA hybridization values and average nucleotide identities values for species delineation (70 and 95-96 %, respectively) between the five strains and their nearest type strains indicated that each strain represented a novel species. All strains were aerobic, Gram-stain-negative, mesophilic, rod-shaped and catalase- and oxidase-positive, with red to pink coloured colonies. The genome sizes of the five strains varied from 4.8 to 7.1 Mb and their G+C contents were between 54.1 and 59.4 mol%. Based on their phenotypic, chemotaxonomic and genotypic characteristics, we propose to classify these isolates into five novel species within the genus Hymenobacter for which we propose the names, Hymenobacter cellulosilyticus sp. nov., Hymenobacter cellulosivorans sp. nov., Hymenobacter aerilatus sp. nov., Hymenobacter sublimis sp. nov. and Hymenobacter volaticus sp. nov., with strains 5116 S-3T (=KACC 21925T=JCM 35216T), 5116 S-27T (=KACC 21926T=JCM 35217T), 5413 J-13T (=KACC 21928T=JCM 35219T), 5516 S-25T (=KACC 21931T=JCM 35222T) and 5420 S-77T (=KACC 21932T=JCM 35223T) as the type strains, respectively.

Dyadobacter pollutisoli sp. nov., isolated from plastic waste landfill soil.

A Gram-stain-negative, yellow-pigmented and facultatively aerobic bacterium, designated strain U1T, was isolated from plastic dumped soil sampled in the Republic of Korea. Cell of strain U1T were non-motile rods showing catalase-negative and oxidase-positive activities. Strain U1T was shown to grow at 10-37 °C (optimum, 25-30 °C) and pH 6.0-9.0 (optimum, pH 8.0), and in the presence of 0-0.5 % (w/v) NaCl (optimum, 0 %). Strain U1T contained iso-C15 : 0, C16 : 0, C16 : 1 ω5c and summed feature 3 (comprising C16 : 1 ω6c and/or C16 : 1 ω7c) as the major cellular fatty acids (>5 %) and menaquinone-7 as the sole respiratory quinone. Phosphatidylethanolamine, two unidentified aminolipids and three unidentified lipids were identified as the major polar lipids. The DNA G+C content of strain U1T calculated from the whole-genome sequence was 45.5 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain U1T formed a distinct phylogenetic lineage within the genus Dyadobacter. Strain U1T has the highest 16S rRNA sequence similarity to Dyadobacter bucti QTA69T (97.9 %). Average nucleotide identity and digital DNA-DNA hybridization values between strain U1T and D. bucti QTA69T were 74.6 % and 18.9 %, respectively. Based on phenotypic, chemotaxonomic and molecular features, strain U1T represents a novel species of the genus Dyadobacter, for which the name Dyadobacter pollutisoli sp. nov. is proposed. The type strain is U1T (= KACC 22210T=JCM 34491T).

Hymenobacter canadensis sp. nov., isolated from freshwater of the pond in Cambridge Bay, Canada.

A Gram-stain-negative, aerobic, reddish-coloured, rod-shaped and non-motile strain PAMC 29467T, was isolated from freshwater of the pond in Cambridge Bay, Canada. Strain PAMC 29467T was closely related to Hymenobacter yonginensis (98.1 % 16S rRNA gene similarity). Genomic relatedness analyses showed that strain PAMC 29467T is distinguishable from H. yonginensis based on average nucleotide identity (91.3 %) and digital DNA-DNA hybridization values (39.3 %). The major fatty acids (>10 %) of strain PAMC 29467T were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C15 : 0 iso, C16 : 1 ω5c and summed feature 4 (C17 : 1 iso l and/or anteiso B). The major respiratory quinone was menaquinone-7. The genomic DNA G+C content was 61.5 mol%. Strain PAMC 29467T was separated from the type species in the genus Hymenobacter by its distinct phylogenetic position and some physiological characteristics. As a result, a novel species is proposed, with the name Hymenobacter canadensis sp. nov. (type strain, PAMC 29467T=KCTC 92787T=JCM 35843T).

Ideonella oryzae sp. nov., isolated from soil, and Spirosoma liriopis sp. nov., isolated from fruits of Liriope platyphylla.

Gram-negative, aerobic, motile by means of two or more polar or subpolar flagella, rod-shaped strain NS12-5T and Gram-negative, facultatively anaerobic, yellow-coloured, rod-shaped strain RP8T were isolated from rice rhizosphere soil and fermented fruits of Liriope platyphylla in the Republic of Korea, respectively. The result of phylogenetic analyses based on 16S rRNA gene sequences showed that strain NS12-5T was most closely related to Ideonella aquatica 4Y11T with 99.79 % sequence similarity. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain NS12-5T and species of the genus Ideonella were 75.6-91.7 % and 20.3-43.9 %, respectively. Growth occurred at 15-40 °C and pH 5-11, and NaCl was not needed for growth. The major fatty acids of strain NS12-5T were summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c) and C16 : 0, and the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The DNA G+C content of strain NS12-5T was 69.03 mol%. The result of phylogenetic analyses based on 16S rRNA gene sequences revealed that strain RP8T was most closely related to Spirosoma aureum BT328T with 96.01 % sequence similarity. The ANI and dDDH values between strain RP8T and reference strains of the genus Spirosoma were 72.9-76.4 % and 18.6-20.0 %, respectively. Growth occurred at 15-37 °C and pH 5-11, and NaCl was not needed for growth. The major fatty acids of strain RP8T were summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c), C16 : 1 ω5c and iso-C15 : 0. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The DNA G+C contents of strain RP8T were 54.9 mol%. Based on phenotypic, genomic and phylogenetic results, strains NS12-5T and RP8T represent novel species in the genus Ideonella and Spirosoma, respectively, and the names Ideonella oryzae sp. nov. and Spirosoma liriopis sp. nov. are proposed. The type strain of I. oryzae sp. nov. is NS12-5T (=KACC 22691T=TBRC 16346T) and the type strain of S. liriopis is RP8T (=KACC 22688T=TBRC 16345T).

Hymenobacter endophyticus sp. nov., isolated from wheat leaf tissue.

A bacterium, designated strain ZK17L-C2T, was isolated from the leaf tissues of wheat (Triticum aestivum) collected in Chengdu, Sichuan Province, PR China. It is aerobic, non-motile, Gram-negative, rod-shaped and red-to-pink in colour. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZK17L-C2T belonged to the genus Hymenobacter and was most closely related to Hymenobacter rigui KCTC 12533T (98.68 %) and Hymenobacter metallilatus 9PBR-2T (98.19 %). Digital DNA-DNA hybridization (dDDH) values between strain ZK17L-C2T and these two type strains were 26.6 and 26.5 %, and average nucleotide identity (ANI) values were 84.9 and 84.8 %, respectively; these values are lower than the proposed and generally accepted species boundaries for dDDH and ANI. The genomic DNA G+C content of strain ZK17L-C2T was 59.4 mol%. It can grow at pH 5.5-7.5 and 15-30 °C, which is different from the closely related type strains. The major fatty acids of strain ZK17L-C2T were iso-C15 : 0, C16 : 0 and C18 : 0. Overall, the results from biochemical, chemical taxonomy and phylogenetic analyses indicate that strain ZK17L-C2T (=CGMCC 1.19373T=KCTC 92184 T) represents a new species of the genus Hymenobacter, for which the name Hymenobacter endophyticus sp. nov. is proposed.

Description of Hymenobacter sediminicola sp. nov., isolated from contaminated sediment.

A polyphasic taxonomic study was conducted on two Gram-negative, non-sporulating, non-motile bacterial strains, S2-20-2T and S2-21-1, isolated from a contaminated freshwater sediment in China. Comparative 16S rRNA gene sequence studies revealed a clear affiliation of two strains with Bacteroidetes, which showed the highest pairwise sequence similarities with Hymenobacter duratus BT646T (99.3%), Hymenobacter psychrotolerans Tibet-IIU11T (99.3%), Hymenobacter kanuolensis T-3T (97.6%), Hymenobacter swuensis DY53T (96.9%), Hymenobacter tenuis POB6T (96.8%), Hymenobacter seoulensis 16F7GT (96.7%), and Hymenobacter rigui KCTC 12533T (96.5%). The phylogenetic analysis based on 16S rRNA gene sequences showed that two strains formed a clear phylogenetic lineage with the genus Hymenobacter. Major fatty acids were identified as iso-C15:0, anteiso-C15:0, and summed feature 3 (C16:1 ω6c and/or C16:1 ω7c/t) and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B). Major cellular polar lipids were identified as phosphatidylethanolamine, three unidentified aminolipids, an unidentified aminophosopholipid and an unidentified lipid. The respiratory quinone was detected as MK-7 and the genomic DNA G + C content was determined to be 57.9% (genome) for type strain S2-20-2T and 57.7 mol% (HPLC) for strain S2-21-1. The observed ANI and dDDH values between strain S2-20-2T and its closely related strains were 75.7-91.4% and 21.2-43.9%, respectively. Based on physiological, biochemical, genetic and genomic characteristics, we propose that strains S2-20-2T and S2-21-1 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter sediminicola sp. nov. is proposed. The type strain is S2-20-2T (= CGMCC 1.18734T = JCM 35801T).

Description of Tellurirhabdus bombi sp. nov., Isolated from Bumblebee.

A Gram-stain-negative, aerobic, non-motile, and rod-shaped bacterium, designated IE-0392T, was isolated from a bumblebee. The 16S rRNA gene sequence (highest 16S rRNA gene sequence similarity with the type strain of Tellurirhabdus rosea (90.0%) and phylogenetic analysis suggest that strain IE-0392T was a member of the genus Tellurirhabdus. Strain IE-0392T optimally grew at 25 â„ƒ and pH 7.0. Menaquinone 7 (MK-7) was the only isoprenoid quinone present in strain IE-0392T. The major fatty acids (> 10%) of strain IE-0392T were iso-C15:0, C16:1 ω5c, and iso-C17:0 3-OH. The polar lipids of strain IE-0392T were phosphatidylethanolamine, phosphatidylserine, unidentified aminophospholipids, unidentified aminolipid, unidentified phospholipid, and unidentified lipids. The genomic DNA G + C content of strain IE-0392T was 48.8%. The amino acid identity (AAI) and the average nucleotide identity (ANI) values suggest that strain IE-0392T is a novel member of the genus Tellurirhabdus. The results suggest that strain IE-0392T represents a novel species of the genus Tellurirhabdus, for which the name Tellurirhabdus bombi sp. nov., is proposed. The type strain is IE-0392T (= GDMCC 1.2794T = JCM 35040T).

NMR solution structures of Runella slithyformis RNA 2'-phosphotransferase Tpt1 provide insights into NAD+ binding and specificity.

Tpt1, an essential component of the fungal and plant tRNA splicing machinery, catalyzes transfer of an internal RNA 2'-PO4 to NAD+ yielding RNA 2'-OH and ADP-ribose-1',2'-cyclic phosphate products. Here, we report NMR structures of the Tpt1 ortholog from the bacterium Runella slithyformis (RslTpt1), as apoenzyme and bound to NAD+. RslTpt1 consists of N- and C-terminal lobes with substantial inter-lobe dynamics in the free and NAD+-bound states. ITC measurements of RslTpt1 binding to NAD+ (KD ∼31 µM), ADP-ribose (∼96 µM) and ADP (∼123 µM) indicate that substrate affinity is determined primarily by the ADP moiety; no binding of NMN or nicotinamide is observed by ITC. NAD+-induced chemical shift perturbations (CSPs) localize exclusively to the RslTpt1 C-lobe. NADP+, which contains an adenylate 2'-PO4 (mimicking the substrate RNA 2'-PO4), binds with lower affinity (KD ∼1 mM) and elicits only N-lobe CSPs. The RslTpt1·NAD+ binary complex reveals C-lobe contacts to adenosine ribose hydroxyls (His99, Thr101), the adenine nucleobase (Asn105, Asp112, Gly113, Met117) and the nicotinamide riboside (Ser125, Gln126, Asn163, Val165), several of which are essential for RslTpt1 activity in vivo. Proximity of the NAD+ ß-phosphate to ribose-C1″ suggests that it may stabilize an oxocarbenium transition-state during the first step of the Tpt1-catalyzed reaction.

Substrate analogs that trap the 2'-phospho-ADP-ribosylated RNA intermediate of the Tpt1 (tRNA 2'-phosphotransferase) reaction pathway.

The enzyme Tpt1 removes an internal RNA 2'-PO4 via a two-step reaction in which: (i) the 2'-PO4 attacks NAD+ to form an RNA-2'-phospho-(ADP-ribose) intermediate and nicotinamide; and (ii) transesterification of the ADP-ribose O2″ to the RNA 2'-phosphodiester yields 2'-OH RNA and ADP-ribose-1″,2″-cyclic phosphate. Because step 2 is much faster than step 1, the ADP-ribosylated RNA intermediate is virtually undetectable under normal circumstances. Here, by testing chemically modified nucleic acid substrates for activity with bacterial Tpt1 enzymes, we find that replacement of the ribose-2'-PO4 nucleotide with arabinose-2'-PO4 selectively slows step 2 of the reaction pathway and results in the transient accumulation of high levels of the reaction intermediate. We report that replacing the NMN ribose of NAD+ with 2'-fluoroarabinose (thereby eliminating the ribose O2″ nucleophile) results in durable trapping of RNA-2'-phospho-(ADP-fluoroarabinose) as a "dead-end" product of step 1. Tpt1 enzymes from diverse taxa differ in their capacity to use ara-2″F-NAD+ as a substrate.

Aquirufa lenticrescens sp. nov. and Aquirufa aurantiipilula sp. nov.: two new species of a lineage of widespread freshwater bacteria.

Two bacterial strains, 9H-EGSET and 15D-MOBT, were isolated from small freshwater habitats located near Salzburg, Austria. They showed the highest 16S rRNA sequence similarities of 100% and 99.9%, respectively, with type strains of species of the genus Aquirufa (Bacteroidota). Genome-based phylogenetic reconstructions with 119 amino acid sequences assigned the new taxa to the two distinct branches of the genus Aquirufa. Whole-genome average nucleotide identities were calculated with all possible pairs belonging to the genus. Values between 75.4% and 88.6% revealed that the two new strains represent each a new species. Like all, so far described members of the genus, they grew aerobically and chemoorganotrophically, were rod-shaped, red-pigmented, and motile by gliding, and showed genome sizes of about 3 Mbp and G + C values of about 40%. They could be distinguished by some phenotypic and chemotaxonomic features from their nearest related species. Until now, strain 9H-EGSET is the only one among the Aquirufa strains which contained traces of MK8 as respiratory quinone, and strain 15D-MOBT is the only one that formed tiny orange globules in liquid medium. The genome of strain 9H-EGSET comprised genes for the complete light-harvesting rhodopsin / retinal system, in the case of 15D-MOBT genes predicted for a nitrous oxide reductase were present. For the two new species of the genus Aquirufa, we propose to establish the names Aquirufa lenticrescens for strain 9H-EGSET (= JCM 34077 T = CIP 111926 T) and Aquirufa aurantiipilula for strain 15D-MOBT (= JCM 34078 T = CIP 111925 T).

Hymenobacter lucidus sp. nov., and Hymenobacter nitidus sp. nov., isolated from soil.

Two novel bacterial strains BT178T and BT635T were isolated from soil collected in Gyeonggi province, Republic of Korea. Both strains were Gram-negative, rod-shaped circular, and had convex, glistening, pink-colored colonies. Phylogenetic analysis based on 16S rRNA gene sequences showed that each of the strains BT178T and BT635T formed an individual lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia, phylum Bacteroidetes). The 16S rRNA gene sequence similarity between the two strains BT178T and BT635T were 97.7%. Both strains had Q-7 as the major respiratory quinone and phosphatidylethanolamine (PE) as the major polar lipids. The main cellular fatty acids of strain BT178T were iso-C15:0, anteiso-C15:0, and those of strain BT635T were iso-C15:0 and Summed Feature 4 (iso-C17:1 I / anteiso-C17:1 B). Based on the result of polyphasic taxonomic analysis, two novel species, Hymenobacter lucidus BT178T (= KCTC 72333T = NBRC 115442T) and Hymenobacter nitidus BT635T (= KACC 21904T = NBRC 115443T) were proposed.

Dyadobacter diqingensis sp. nov., isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China.

A Gram-negative, aerobic, nonmotile, rod-shaped and yellow-pigment-producing bacteria was isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China and characterized using a polyphasic approach. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM B04101T was closely related to the type strain of Dyadobacter koreensis DSM 19938T (97.81%) and Dyadobacter frigoris AR-3-8T (97.95%). The predominant respiratory quinone was menaquinone-7 (MK-7). The major polar lipid was phosphatidylethanolamine. The major fatty acids were summed feature 3 (C16:1ω7c/C16:1ω6c), C18:1ω9c and C16:0. The DNA G + C content was 43.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain YIM B04101T belonged to a cluster comprising species of the genus Dyadobacter. However, it differed from its closest relative, Dyadobacter koreensis KCTC 12537T and Dyadobacter frigoris AR-3-8T, in many physiological properties. Based on these phenotypic characteristics and phylogenetic distinctiveness, strain YIM B04101T is considered to be a novel species of the genus Dyadobacter, for which the name Dyadobacter diqingensis sp. nov. is proposed. The type strain is YIM B04101T (= CGMCC 1.19249T = CCTCC AB 2021270).

Hymenobacter translucens sp. nov. and Hymenobacter pini sp. nov. isolated from soil.

Two novel bacterial strains BT175T and BT728T were isolated from soil collected in the Republic of Korea. Both strains were Gram stain negative, rod shaped, and had circular, convex, and pink-colored colonies. The 16S rRNA gene sequence similarity between the strains BT175T and BT728T was 93.6%, indicating that they represent a distinct species. 16S rRNA sequence analysis indicated that strains BT175T and BT728T belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia, phylum Bacteroidetes). Strain BT175T was closely related to Hymenobacter persicinus 1-3-3-3T (97.2%, 16S rRNA gene similarity), Hymenobacter knuensis 16F7C-2T (96.6%), and Hymenobacter daejeonensis PB105T (96.1%). Strain BT728T was closely related to Hymenobacter rigui KCTC 12533T (98.4%), Hymenobacter metallilatus 9PBR-2T (97.6%), and Hymenobacter perfusus LMG26000T (97.4%). Strain BT175T and BT728T were found to have the MK-7 as the major respiratory quinone. The DNA G + C content of strain BT175T was 61.6 mol% and BT728T was 59.6 mol%, respectively. Characterization based on polyphasic analysis indicated that strains BT175T and BT728T represent novel species of the genus Hymenobacter and the names Hymenobacter translucens sp. nov. and Hymenobacter pini sp. nov. are proposed. The type strain of Hymenobacter translucens is BT175T (= KCTC 72330T = NBRC 115441T) and Hymenobacter pini is BT728T (= KACC 22629T = NBRC 115444T).

Hymenobacter cyanobacteriorum sp. nov., isolated from a freshwater reservoir during the cyanobacterial bloom period.

A Gram-negative, red-colored, and rod-shaped bacterial strain, DH14T, was isolated from a eutrophic reservoir. The 16S rRNA gene sequence analysis showed that strain DH14T was most closely related to Hymenobacter terrigena (98.3% similarity) and Hymenobacter terrae (98.1%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain DH14T and its related type strains were below 82.9% and 27.2%, respectively. Strain DH14T contained iso-C15:0 (32.6%), anteiso-C15:0 (14.0%), and summed feature 3 (C16:1 ω6c and/or C16:1 ω7c) (25.8%) as major cellular fatty acids. The main polar lipids were phosphatidylethanolamine, two unidentified aminophospholipids, and one unidentified lipid. The respiratory quinone was menaquinone 7 (MK-7). The genomic DNA G + C content was 62.1%. These evidences support the classification of strain DH14T as a novel species in the genus Hymenobacter, for which the name Hymenobacter cyanobacteriorum sp. nov. is proposed. The type strain is DH14T (= KCTC 92040T = LMG 32425T).

Hymenobacter terricola sp. nov., isolated from Antarctic soil.

Strain 3F2T was isolated from a soil sample obtained from the surface of Deception Island, Antarctica. The isolate was a Gram-stain-negative, aerobic, non-motile, rod-shaped bacterium, and its colonies were red to pink in colour. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 3F2T belonged to the genus Hymenobacter, family Hymenobacteraceae and was most closely related to Hymenobacter sedentarius DG5BT (97.0% sequence similarity), Hymenobacter soli PB17T (96.9%), Hymenobacter terrae DG7AT (96.8%) and Hymenobacter rufus S1-2-2-6T (96.5%). Growth occurred at 4-20 °C (optimum, 10 °C), up to 1.0 % (w/v) NaCl (optimum, 0%) and pH 6.0-8.0 (optimum, pH 7.0). The chemotaxonomic characteristics of strain 3F2T, which had MK-7 as its predominant menaquinone and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), iso-C15:0, anteiso-C15:0 and C16:1 ω5c as its major fatty acids, were consistent with classification in the genus Hymenobacter. The polar lipid profile of strain 3F2T comprised phosphatidylethanolamine, two unidentified aminolipids, two unidentified aminophospholipids and three unidentified polar lipids. The genome of strain 3F2T was 6.56 Mbp with a G+C content of 61.5 mol%. Average nucleotide identity (ANI) values between 3F2T and the other species of the genus Hymenobacter were found to be low (ANIm <87.0%, ANIb <82.0% and OrthoANIu <83.0%). Furthermore, digital DNA-DNA hybridization and average amino acid identity values between strain 3F2T and the closely related species ranged from 20.0 to 26.3% and from 64.0 to 81.1 %, respectively. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain 3F2T represents a novel species within the genus Hymenobacter, for which the name Hymenobacter terricola sp. nov. is proposed. The type strain is 3F2T (=KCTC 72468T=CGMCC 1.13716T).