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.

Comparative genomics and molecular adaptational analysis of Arthrobacter from Sikkim Himalaya provided insights into its survivability under multiple high-altitude stress.

Arthrobacter is a dominant aerobic bacterium under the class Actinobacteria, known for its nutritionally versatile nature and wide prevalence in stressful environments. In the current study representative two strains of Arthrobacter, ERGS1:01 and ERGS4:06, with efficient survivability under high altitude stress conditions were selected for comparative genomic studies with their mesophilic counterparts. Physiological analysis and genome insights supported the survival of these strains under multiple high-altitude stress conditions. Molecular cold-adaptation and substitution analysis of the studied strains supported the incidence of more cold-adapted proteins for functionality at low temperatures. Studied strains preferred amino acids like serine, asparagine, lysine, tryptophan for favoring increased flexibility supporting their broad temperature survivability. To the best of our knowledge, this is the first molecular cold adaptation analysis performed for the genus Arthrobacter and has revealed that 'aromaticity', one of the cold-adaptor indicators, should be carefully considered while evaluating cold adaptation strategies in psychrotrophic/psychrophilic bacteria.

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 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).

A case of infective endocarditis caused by Arthrobacter woluwensis.

Corynebacteria are rare causative agents of infective endocarditis. This is a reported case of a destructive aorto-mitral infective endocarditis caused by Arthrobacter woluwensis. Microbial identification was achieved by 16S rRNA polymerase chain reaction on valve tissue samples. Outcome was favorable after surgical valve replacement and 4-week antibiotic treatment.

Biological and chemical characterization of antimicrobial activity in Arthrobacter spp. isolated from disease-suppressive compost.

Antagonistic bacteria can act as biocontrol agents against various phytopathogens. Recently, Arthrobacter spp. demonstrated antifungal activity, but were not further characterized. In this study, the antimicrobial activity of Arthrobacter humicola strains M9-1A, M9-2, and M9-8, and Arthrobacter psychrophenolicus strain M9-17 were evaluated against nine plant pathogens in vitro, and their cell-free filtrates were additionally assessed for inhibition of Alternaria alternata and suppression of black mold disease on tomato fruit. Results indicated that A. humicola M9-1A and A. psychrophenolicus M9-17 were the most inhibitory, reducing growth of seven of the pathogens studied. Cell-free filtrates of A. psychrophenolicus M9-17 reduced the growth of most pathogens. All cell-free bacterial filtrates, except those from A. humicola M9-2, suppressed black mold on tomato fruit. Disk diffusion assays with ethyl acetate soluble culture filtrate extracts of all bacteria reduced the mycelial growth of A. alternata. Clear inhibition zones were observed for A. psychrophenolicus M9-17 extracts using drop bioassays. The antifungal compound N-acetyltryptamine was purified and characterized from the A. psychrophenolicus M9-17 cell-free ethyl acetate soluble extract. This study suggests that antibiosis may play a key role in the antimicrobial activity of Arthrobacter spp.

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 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 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 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).

Arthrobacter celericrescens sp. nov., isolated from forest soil.

A novel bacterial strain, designated NEAU-SA2T, was isolated from forest soil collected from the Zhangjiajie city, Hunan Province, PR China and characterised using a polyphasic approach. The cells were aerobic, Gram-stain-positive, non-flagellated and rod-coccus-shaped. The strain grew optimally at 28 °C, pH 7.0 and with 0 % NaCl (w/v). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the organism should be assigned to the genus Arthrobacter and was closely related to Arthrobacter cupressi DSM 24664T (98.89 %) and Arthrobacter silvisoli CCTCC AB 2017271T (98.41 %), which was further confirmed by multilocus sequence analysis. The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and C16 : 0; MK-9(H2) was the predominant respiratory quinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified glycolipid. The peptidoglycan type was A3α, and the cell-wall sugars were glucose and galactose. The genomic G+C content of strain NEAU-SA2T was 67.04 mol%. The average nucleotide identity values between NEAU-SA2T and A. cupressi DSM 24664T and A. silvisoli CCTCC AB 2017271T were 88.57-90.94 %. The digital DNA-DNA hybridisation values between strain NEAU-SA2T and its most closely related species were 37.00 and 41.10 %, respectively, again indicating that they belong to different taxa. Therefore, strain NEAU-SA2T represents a novel species of the genus Arthrobacter, for which the name Arthrobacter celericrescens sp. nov. is proposed. The type strain is NEAU-SA2T (=DSM 106718T=CCTCC AB 2017272T).

Heavy metal resistance genes and plasmid-mediated quinolone resistance genes in Arthrobacter sp. isolated from Brazilian soils.

Arthrobacter sp. are Gram-positive bacilli commonly obtained from soil and in the hospital environment. These species have been reported to cause several types of infection. Heavy metals are a threat to the ecological system due to their high-levels of toxicity and the fluoroquinolones are antimicrobials widely used for the treatment of different bacterial infections. The aim of this study was to investigate the resistance to fluoroquinolone and heavy metals, the presence of plasmid-mediated resistance (PMQR) genes and heavy metals resistance (HMR) genes and the presence of plasmids in Arthrobacter sp. obtained from Brazilian soils. Bacterial isolation was performed using soil samples from different Brazilian regions. The bacterial identification was performed by 16S rRNA gene sequencing. The resistance profile for fluoroquinolones and heavy metals was determined by MIC. Several PMQR and HMR genes and plasmid families were investigated by PCR. Eight isolates were obtained from soil samples from different cultivations and regions of Brazil. All isolates were resistant to all fluoroquinolones, cadmium, cobalt and zinc and the majority to copper. Among the PMQR genes, the qepA (4) was the most prevalent, followed by qnrS (3), qnrB (3), oqxB (2) and oqxA (1). Among the HMR genes, the copA was detected in all isolates and the czcA in two isolates. The replication origin of the ColE-like plasmid was detected in all isolates; however, no plasmid was detected by extraction. The association of resistance to heavy metals and antimicrobials is a threat to the environmental balance and to human health. There are no studies reporting the association of PMQR and HMR genes in bacteria belonging to the genus Arthrobacter. To the best of our knowledge, this is the first report of qnrB, qepA, oqxA and oqxB in Arthrobacter species.

Arthrobacter ruber sp. nov., isolated from glacier ice.

A Gram-stain-positive strain designated MDB1-42T was isolated from ice collected from Midui glacier in Tibet, PR China. Strain MDB1-42T was catalase-positive, oxidase-negative and grew optimally at 25-28 °C and pH 7.0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that MDB1-42T represented a member of the genus Arthrobacter. The highest level of 16S rRNA gene sequence similarity (99.86 %) was found with Arthrobacter agilis NBRC 15319T. Multilocus sequence analysis revealed low similarity of 91.93 % between MDB1-42T and Arthrobacter agilis NBRC 15319T. Average nucleotide identity and digital DNA-DNA hybridization values between MDB1-42T and the most closely related strain, Arthrobacter agilis DSM 20550T, were 81.36 and 24.5 %, respectively. The genomic DNA G+C content was 69.0 mol%. The major cellular fatty acids of MDB1-42T were anteiso-C15 : 0 and anteiso-C17:0. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, one unidentified glycolipid and one unidentified lipid. The predominant menaquinone was MK-9(H2). On the basis of results obtained using a polyphasic approach, a novel species Arthrobacter ruber sp. nov. is proposed, with MDB1-42T (=CGMCC 1.9772T=NBRC 113088T) as the type strain.

Arthrobacter paludis sp. nov., isolated from a marsh.

A novel Gram-stain-positive, strictly aerobic, non-endospore-forming bacterium, designated CAU 9143T, was isolated from a hydric soil sample collected from Seogmo Island in the Republic of Korea. Strain CAU 9143T grew optimally at 30 °C, at pH 7.0 and in the presence of 1 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences revealed that strain CAU 9143T belonged to the genus Arthrobacter and was closely related to Arthrobacter ginkgonis SYP-A7299T (97.1 % similarity). Strain CAU 9143T contained menaquinone MK-9 (H2) as the major respiratory quinone and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, two glycolipids and two unidentified phospholipids as the major polar lipids. The whole-cell sugars were glucose and galactose. The peptidoglycan type was A4a (l-Lys-D-Glu2) and the major cellular fatty acid was anteiso-C15 : 0. The DNA G+C content was 64.4 mol% and the level of DNA-DNA relatedness between CAU 9143T and the most closely related strain, A. ginkgonis SYP-A7299T, was 22.3 %. Based on phenotypic, chemotaxonomic and genetic data, strain CAU 9143T represents a novel species of the genus Arthrobacter, for which the name Arthrobacterpaludis sp. nov. is proposed. The type strain is CAU 9143T (=KCTC 13958T,=CECT 8917T).

Arthrobacter silvisoli sp. nov., isolated from forest soil.

A novel Gram-stain-positive, strictly aerobic strain, NEAU-SA1T, which showed a rod-coccus growth life cycle, was isolated from forest soil from Zhangjiajie, Hunan Province, China. The isolate grew at 10-40 °C (optimum 28 °C), at pH 5.0-10.0 (optimum pH 7.0) and in the presence of up to 5 % (w/v) NaCl, although NaCl was not required for growth. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-SA1T belonged to the genus Arthrobacter and was closely related to Arthrobacter cupressi DSM 24664T (98.1 % similarity). Average nucleotide identity values between NEAU-SA1T and A. cupressi DSM 24664T were 88.91 and 87.41 % by ANIm and ANIb analysis, respectively. The in silico DNA-DNA hybridization value between strain NEAU-SA1T and A. cupressi DSM 24664T was 34.20 %, again indicating they belong to different taxa. The genomic DNA G+C content was 66.74 mol%. The major cellular fatty acids (>10 %) were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and two unidentified glycolipids. The predominant menaquinone was MK-9(H2). The peptidoglycan type was A3α with an interpeptide bridge comprising l-Lys and l-Ala. Glucose, ribose and galactose were the whole-cell sugars. On the basis of morphological, physiological, biochemical and chemotaxonomic analysis, strain NEAU-SA1T was classified as representing a novel species in the genus Arthrobacter, for which the name Arthrobacter silvisoli sp. nov. is proposed. The type strain is NEAU-SA1T (=DSM 106716T=CCTCC AB 2017271T).

Isolation and characterization of a novel nicotinophilic bacterium, Arthrobacter sp. aRF-1 and its metabolic pathway.

Nicotine is a potent parasympathomimetic stimulant and an important natural alkaloid mainly found in the Nicotiana genus of plants. It can directly threaten ecological security and human health in tobacco waste, wastewater, and other forms of tobacco production. Therefore, it is the basis of nicotine pollution prevention and of great application value to explore efficient and a wide range of nicotinophilic bacteria for tobacco industry and environmental protection. In this study, one nicotinophilic bacterium was isolated from the soil, which accumulated tobacco waste over 50 years at a Hefei cigarette factory. The strain was named aRF-1, which was identified as Arthrobacter sp. by analysis. The nicotine degradation tests showed that the optimum temperature for cell growth and metabolism of nicotine of Arthrobacter sp. aRF-1 was 30 °C, and the optimum initial pH value was about 7.0. Under the optimum experimented conditions, it can tolerance nicotine concentration as high as 8 g·L-1 . The highest removal rate of nicotine was 93.8% in 72 H in nonsterilization contaminated soil by Arthrobacter sp. aRF-1. LC-MS/MS was used to analyze the nicotine metabolic intermediates of strain Arthrobacter sp. aRF-1. A total of nine major metabolites that were detected were able to metabolize nicotine along a variant pathway of pyridine and pyrrolidine, and there may be more than two nicotine metabolic pathways for Arthrobacter sp. aRF-1 through the analysis of the main intermediate products.

Biochemical pathways and enhanced degradation of di-n-octyl phthalate (DOP) in sequencing batch reactor (SBR) by Arthrobacter sp. SLG-4 and Rhodococcus sp. SLG-6 isolated from activated sludge.

Two bacterial strains designated as Arthrobacter sp. SLG-4 and Rhodococcus sp. SLG-6, capable of utilizing di-n-octyl phthalate (DOP) as sole source of carbon and energy, were isolated from activated sludge. The analysis of DOP degradation intermediates indicated Arthrobacter sp. SLG-4 could completely degrade DOP. Whereas DOP could not be mineralized by Rhodococcus sp. SLG-6 and the final metabolic product was phthalic acid (PA). The proposed DOP degradation pathway by Arthrobacter sp. SLG-4 was that strain SLG-4 initially transformed DOP to PA via de-esterification pathway, and then PA was metabolized to protocatechuate acid and eventually converted to tricarboxylic acid (TCA) cycle through meta-cleavage pathway. Accordingly, Phthalate 3,4-dioxygenase genes (phtA) responsible for PA degradation were successfully detected in Arthrobacter sp. SLG-4 by real-time quantitative PCR (q-PCR). q-PCR analysis demonstrated that the quantity of phthalate 3,4-dioxygenase was positively correlated to DOP degradation in SBRs. Bioaugmentation by inoculating DOP-degrading bacteria effectively shortened the start-up of SBRs and significantly enhanced DOP degradation in bioreactors. More than 91% of DOP (500 mg L-1) was removed in SBR bioaugmented with bacterial consortium, which was double of the control SBR. This study suggests bioaugmentation is an effective and feasible technique for DOP bioremediation in practical engineering.

Arthrobacter silviterrae sp. nov., isolated from forest soil.

A novel actinomycete strain, designated KIS14-16T, was isolated from forest soil in Ongjin county, South Korea and characterized using polyphasic taxonomy. The cells are aerobic, Gram-stain-positive, non-flagellated and short rods. The strain grew in a temperature range of 4-33 °C (optimum, 28-30 °C) and pH range of 5.0-10.0 (optimum, 7.0) and in the presence of 0-5 % (w/v) NaCl (optimum, 0 %). Comparison of 16S rRNA gene sequences showed that strain KIS14-16T is a member of the genus Arthrobacter exhibiting high sequence similarity with A. livingstonensis LI2T (97.7 %), A. cryoconiti Cr6-08T (97.6 %), A. psychrochitiniphilus GP3T (97.4 %), A. stackebrandtii CCM 2783T (97.1 %) and A. globiformis DSM 20124T (96.3 %). DNA-DNA relatedness and phenotypic data distinguished strain KIS14-16T from phylogenetically related type strains. The peptidoglycan type of strain KIS14-16T was A3α, with an interpeptide bridge comprising l-Lys, l-Thr, Gly and l-Ala4. Strain KIS14-16T contained a large amount of MK-9(H2) and relatively small amounts of MK-10(H2) and MK-8(H2). The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and dimannosylglyceride. The major fatty acids (>10 %) were anteiso-C15 : 0 and anteiso-C17 : 0. The genomic DNA G+C content was 63.9 mol%. On the basis of these phenotypic, chemotaxonomic and phylogenetic data, strain KIS14-16T should be designated as a representative novel species of the genus Arthrobacter, for which the name Arthrobacter silviterrae sp. nov. is proposed. The type strain is KIS14-16T (=KACC 17303T=DSM 27180T=NBRC 109660T).