Arthrobacter horti sp. nov., isolated from mountain soil.

Gram-stain-positive, aerobic, rod-shaped strains, YJM1T and YJM12S, were isolated from Maebong Mountain, Dogok-dong, Gangnam-gu, Seoul, Republic of Korea. Strains YJM1T and YJM12S exhibited growth at 5-35 °C (optimum, 20-30 °C) and pH 6-9 (optimum, pH 7) and in 0-4 % (w/v) NaCl. Strains YJM1T and YJM12S showed highest 16S rRNA gene sequence similarity to the following members of the genus Arthrobacter: A. nanjingensis A33T (98.3 %/98.2 % similarity), A. woluwensis NBRC 107840T (98.2 %/98.1 %), A. humicola KV-653T (97.3 %), A. oryzae KV-651T (97.3 %), and A. globiformis NBRC 12137T (97.2 %). The strains grew well on Reasoner's 2A, nutrient, Mueller-Hinton, yeast-dextrose, and glucose-peptone-meat extract agars. The major polar lipids of strain YJM1T were phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylinositol. The primary respiratory quinone of strain YJM1T was MK-9(H2), and the major fatty acids of strains YJM1T and YJM12S were anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, and iso-C16 : 0. The DNA G+C content, based on the whole genome sequence of strain YJM1T, was 68.3 mol%. Average nucleotide identity values and digital DNA-DNA hybridization values between strain YJM1T and the reference strains ranged from 75.0 to 92.7 % and from 21.0 to 65.3 %, respectively. Strain YJM1T exhibited antimicrobial activity against Bacillus subtilis and Escherichia coli. Considering the chemotaxonomic, phenotypic, genotypic, and phylogenetic results, we propose the strain YJM1T represents a novel species in the genus Arthrobacter and suggest the name Arthrobacter horti sp. nov. (type strain YJM1T=KACC 23300T=JCM 36483T).

Arthrobacter sunyaminii sp. nov. and Arthrobacter jiangjiafuii sp. nov., new members in the genus Arthrobacter.

Four novel bacterial strains (zg-ZUI122T/zg-ZUI10 and zg-ZUI227T/zg-ZUI100) were isolated from the intestinal contents of Marmota himalayana and characterized using a polyphasic approach. Cells were Gram-stain- and catalase-positive, urease- and oxidase-negative. Strains grew optimally at 28-30 °C, pH 7.0, with 0.5 % NaCl (w/v). A comparative analysis of 16S rRNA gene sequences revealed that strain pairs zg-ZUI122T/zg-ZUI10 and zg-ZUI227T/zg-ZUI100 belonged to the genus Arthrobacter and were most closely related to Arthrobacter citreus DSM 20133T, with similarities of 99.6 and 99.5 %, respectively. This was further confirmed by phylogenetic analyses based on the 16S rRNA gene and genome sequences. The digital DNA-DNA hybridization and average nucleotide identity values between the two new type strains (zg-ZUI122T and zg-ZUI227T) and other species in the genus Arthrobacter were 20.0-24.4/77.2-83.4% and 19.9-25.1/77.1-83.4%, all below the thresholds. The major cellular fatty acids detected in the two novel species included iso-C15 : 0 and anteiso-C15 : 0; the predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. MK-8(H2) (77.3%) was the predominant respiratory quinone detected in strain zg-ZUI122T, while MK-8(H2) (53.7%) and MK-9(H2) (46.3%) were detected in strain zg-ZUI227T. The shared cell-wall amino acids detected in the two novel species were alanine, glutamic acid and lysine; the shared whole cell wall sugars consisted of galactose, mannose and ribose. All these analyses concluded that these four strains represent two different novel species in the genus Arthrobacter, for which the names Arthrobacter sunyaminii sp. nov. (zg-ZUI122T = GDMCC 1.2502T = KCTC 49677T) and Arthrobacter jiangjiafuii sp. nov. (zg-ZUI227T = GDMCC 1.2500T = KCTC 49676T) are proposed.

Arthrobacter cheniae and Arthrobacter frigidicola sp. nov., isolated from a glacier.

Two Gram-stain-positive, aerobic, rod-shaped, pink and light pink colony-forming bacteria, designated as Hz2T and MDT2-14T, respectively, were isolated from glacier cryoconite samples. Comparisons based on 16S rRNA gene sequences showed that strains Hz2T and MDT2-14T take Arthrobacter bussei KR32T and Arthrobacter zhaoguopingii J391T as their closest neighbours, respectively. The average nucleotide identity values between the two novel strains and their closest relatives were 83.56 and 93.06 %, respectively. The two strains contain MK-9(H2) as their predominant menaquinone. The polar lipids of both strains were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and an unidentified glycolipid. The major fatty acids of strain Hz2T were anteiso-C15 : 0, summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c) and iso-C15 : 0, while the major fatty acids of strain MDT2-14T were anteiso-C15 : 0 and anteiso-C17 : 0. Based on these data, we propose two novel species, Arthrobacter cheniae sp. nov. (Hz2T = CGMCC 1.9262T=NBRC 113086T) and Arthrobacter frigidicola sp. nov. (MDT2-14T=CGMCC 1.9882T=NBRC 113089T).

Genome Analysis and Genomic Comparison of the Novel Species Arthrobacter ipsi Reveal Its Potential Protective Role in Its Bark Beetle Host.

The pine engraver beetle, Ips acuminatus Gyll, is a bark beetle that causes important damages in Scots pine (Pinus sylvestris) forests and plantations. As almost all higher organisms, Ips acuminatus harbours a microbiome, although the role of most members of its microbiome is not well understood. As part of a work in which we analysed the bacterial diversity associated to Ips acuminatus, we isolated the strain Arthrobacter sp. IA7. In order to study its potential role within the bark beetle holobiont, we sequenced and explored its genome and performed a pan-genome analysis of the genus Arthrobacter, showing specific genes of strain IA7 that might be related with its particular role in its niche. Based on these investigations, we suggest several potential roles of the bacterium within the beetle. Analysis of genes related to secondary metabolism indicated potential antifungal capability, confirmed by the inhibition of several entomopathogenic fungal strains (Metarhizium anisopliae CCF0966, Lecanicillium muscarium CCF6041, L. muscarium CCF3297, Isaria fumosorosea CCF4401, I. farinosa CCF4808, Beauveria bassiana CCF4422 and B. brongniartii CCF1547). Phylogenetic analyses of the 16S rRNA gene, six concatenated housekeeping genes (tuf-secY-rpoB-recA-fusA-atpD) and genome sequences indicated that strain IA7 is closely related to A. globiformis NBRC 12137T but forms a new species within the genus Arthrobacter; this was confirmed by digital DNA-DNA hybridization (37.10%) and average nucleotide identity (ANIb) (88.9%). Based on phenotypic and genotypic features, we propose strain IA7T as the novel species Arthrobacter ipsi sp. nov. (type strain IA7T = CECT 30100T = LMG 31782T) and suggest its protective role for its host.

Arthrobacter sulfonylureivorans sp. nov., isolated from a sulfonylurea herbicides degrading consortium enriched with birch forest soil.

A gram-stain positive, aerobic, motile, rod-shaped bacterium, designated strain LAM7117T, was isolated from a sulfonylurea herbicides degrading consortium enriched with birch forest soil. The optimal temperature and pH for the growth of strain LAM7117T were 35 °C and 7.5, respectively. Strain LAM7117T could grow in the presence of NaCl with concentration up to 9% (w/v). Strain LAM7117T formed a distinct phylogenetic subclade within the genus Arthrobacter in the phylogenetic trees built with 16S rRNA gene sequences and shared the highest similarity with A. crystallopoietes JCM 2522T (97.7%). The values of digital DNA-DNA relatedness and Avery Nucleotide Identity based on the genome sequences between LAM7117T and A. crystallopoietes JCM 2522T were 21.4 and 77.4%, respectively. The genomic DNA G + C content was 65.9 mol%. The major cellular fatty acids were anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The cell wall peptidoglycan contained the amino acids as glycine, lysine, alanine and glutamic acid. The major polar lipids present in strain LAM7117T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidyl inositol, two unidentified glycolipids and one unidentified lipid. The predominant menaquinones of strain LAM7117T were MK-8 and MK-9. Based on the phenotypic characteristics, chemotaxonomic data and genotypic analyses, strain LAM7117T should be classified as a novel species of genus Arthrobacter, for which the name Arthrobacter sulfonylureivorans sp. nov. is proposed. The type strain is LAM7117T (= JCM 32824T = CGMCC 1.16681T).

Arthrobacter mobilis sp. nov., a novel actinobacterium isolated from Cholistan desert soil.

A Gram-stain-positive, aerobic, catalase-positive, oxidase-negative, non-mycelium-forming, motile, rod-shaped with one polar flagellum actinobacterium, designated E918T, was isolated from a desert soil collected in Cholistan desert, Pakistan. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain E918T belonged to the genus Arthrobacter and was most closely related to Arthrobacter deserti CGMCC 1.15091T (97.2 % similarity). The peptidoglycan was of the A3α type and the whole-cell sugar profile was found to contain galactose. The major menaquinone was MK-9(H2). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and two unidentified glycolipids. The major fatty acids identified were anteiso-C15 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 68.69 mol%. The digital DNA-DNA hybridization and average nucleotide identity values between strain E918T and A. deserti CGMCC 1.15091T were 28.0 and 83.4%, respectively. On the basis of its phylogenetic, phenotypic and chemotaxonomic features, strain E918T was considered to represent a novel species of the genus Arthrobacter, for which the name Arthrobacter mobilis sp. nov. is proposed. The type strain of Arthrobacter mobilis is E918T (=JCM 33392T=CGMCC 1.16978T).

Arthrobacter yangruifuii sp. nov. and Arthrobacter zhaoguopingii sp. nov., two new members of the genus Arthrobacter.

Four unknown strains belonging to the genus Arthrobacter were isolated from plateau wildlife on the Qinghai-Tibet Plateau of PR China. Phylogenetic analysis based on 16S rRNA gene sequences showed that the four isolates were separated into two clusters. Cluster I (strains 785T and 208) had the greatest 16S rRNA gene sequence similarity to Arthrobacter citreus (98.6 and 98.7 %, respectively), Arthrobacter luteolus (98.0 and 98.1%, respectively), Arthrobacter gandavensis (97.9 and 98.0 %, respectively) and Arthrobacter koreensis (97.6 and 97.7 %, respectively). Likewise, cluster II (strains J391T and J915) had the highest sequence similarity to Arthrobacter ruber (98.6 and 98.3 %, respectively) and Arthrobacter agilis (98.1 and 97.9  %, respectively). Average nucleotide identity and the digital DNA-DNA hybridization values illustrated that the two type strains, 785T and J391T, represented two separate novel species that are distinct from all currently recognized species in the genus Arthrobacter. These strains had DNA G+C contents of 66.0-66.1 mol% (cluster I) and 68.0 mol% (cluster II). The chemotaxonomic properties of strains 785T and J391T were in line with those of the genus Arthrobacter: anteiso-C15:0 (79.3 and 40.8 %, respectively) as the major cellular fatty acid, MK-8(H2) (65.8 %) or MK-9(H2) (75.6 %) as the predominant respiratory quinone, a polar lipid profile comprising diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, glycolipids and phospholipid, and A3α or A4α as the cell wall peptidoglycan type. On the basis of our results, two novel species in the genus Arthrobacter are proposed, namely Arthrobacter yangruifuii sp. nov. (type strain, 785T=CGMCC 1.16725T=GDMCC 1.1592T=JCM 33491T) and Arthrobacter zhaoguopingii sp. nov. (type strain, J391T=CGMCC 1.17382T=GDMCC 1.1667T=JCM 33841T).

Arthrobacter sedimenti sp. nov., isolated from river sediment in Yuantouzhu park, China.

A Gram-stain positive, motile, aerobic and rod-shaped strain (MIC A30T) was isolated from river sediment in Yuantouzhu park, Wuxi City, China. Growth occurred at 20-40 °C, at pH 6.0-9.0 and at 0-5.0% NaCl. Strain MIC A30T was moderately related to Arthrobacter liuii CGMCC 1.12778T (97.9%), Arthrobacter pokkaliiT (97.9%) and Arthrobacter globiformis NBRC 12137T (96.7%) by 16S rRNA analysis. The DNA-DNA relatedness values between strain MIC A30T and these reference strains were below 30%. The DNA G+C content was 63.1 mol%. Average nucleotide identity (ANI) and genome-to-genome distance (GGD) values between strain MIC A30T and A. liuii CGMCC 1.12778T were 60.34% and 29.39%, respectively. Quinone was identified as MK-9(H2). Major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. Major fatty acids were iso-C15:0, anteiso-C15:0 and anteiso-C17:0. Whole-cell sugars were galactose, mannose and rhamnose. The cell wall peptidoglycan contained A4α peptidoglycan type with lysine as the diagnostic diamino acid. Based on several taxonomic results, strain MIC A30T is identified as a novel species in genus Arthrobacter, whose name is proposed as Arthrobacter sedimenti sp. nov. The type strain is MIC A30T (= KACC 19599T = CGMCC 1.13474T).

Arthrobacter bussei sp. nov., a pink-coloured organism isolated from cheese made of cow's milk.

A pink-coloured bacterium (strain KR32T) was isolated from cheese and assigned to the 'Arthrobacter agilis group'. Members of the 'pink Arthrobacter agilis group' form a stable clade (100 % bootstrap value) and contain the species Arthrobacter agilis, Arthrobacter ruber and Arthrobacter echini, which share ≥99.0 % 16S rRNA gene sequence similarity. Isolate KR32T showed highest 16S rRNA gene sequence similarity (99.9 %) to A. agilis DSM 20550T. Additional multilocus sequence comparison confirmed the assignment of strain KR32T to the clade 'pink A. agilis group'. Average nucleotide identity and digital DNA-DNA hybridization values between isolate KR32T and A. agilis DSM 20550T were 82.85 and 26.30 %, respectively. The G+C content of the genomic DNA of isolate KR32T was 69.14 mol%. Chemotaxonomic analysis determined anteiso-C15 : 0 as the predominant fatty acid and MK-9(H2) as the predominant menaquinone. Polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and monoacyldimannosyl-monoacylglycerol. The peptidoglycan type of the isolate was A3α. The carotenoid bacterioruberin was detected as the major pigment. At 10 °C, strain KR32T grew with increased concentrations of bacterioruberin and production of unsaturated fatty acids. Strain KR32T was a Gram-stain-positive, catalase-positive, oxidase-positive and coccus-shaped bacterium with optimal growth at 27-30 °C and pH 8. The results of phylogenetic and phenotypic analyses enabled the differentiation of the isolate from other closely related species of the 'pink A. agilis group'. Therefore, strain KR32T represents a novel species for which the name Arthrobacter bussei sp. nov. is proposed. The type strain is KR32T (=DSM 109896T=LMG 31480T=NCCB 100733T).

Arthrobacter ulcerisalmonis sp. nov., isolated from an ulcer of a farmed Atlantic salmon (Salmo salar), and emended description of the genus Arthrobacter sensu lato.

A Gram-stain positive, pleomorphic, oxidase-negative, non-motile isolate from the ulcer of a farmed Atlantic salmon (Salmo salar), designated strain T11bT, was subjected to a comprehensive taxonomic investigation. A comparative analysis of the 16S rRNA gene sequence showed highest similarities to the type strains of Pseudarthrobacter siccitolerans (98.1 %) and Arthrobacter methylotrophus and Pseudarthrobacter phenanthrenivorans (both 98.0 %). The highest ANI value observed between the assembled genome of T11bT and the publicly available Pseudarthrobacter and Arthrobacter type strain genomes were 81.15 and 80.99 %, respectively. The major respiratory quinone was menaquinone MK-9(H2). The polyamine pattern contained predominantly spermidine. The polar lipid profile consisted of the major lipids diphosphatidylglycerol, phosphatidylglycerol, monogalactosyl-diacylglycerol and dimannosylglyceride. Minor amouts of trimannosyldiacylglycerol and phosphatidylinositol were also detected. The peptidoglycan was of the type A3α l-Lys-l-Ser-l-Thr-l-Ala (A11.23). In the fatty acid profile, anteiso and iso branched fatty acids predominated (anteiso C15 : 0, iso C16 : 0, anteiso C17 : 0). Moderate to low DNA-DNA similarities, physiological traits as well as unique traits in the fatty acid pattern distinguished strain T11bT from the next related species. All these data point to the fact that strain T11bT represents a novel species of the genus Arthrobacter for which we propose the name Arthrobacter ulcerisalmonis sp. nov. The type strain is T11bT (=CIP 111621T=CCM 8854T=LMG 30632T=DSM 107127T).