Simplicispira sedimenti sp. nov., isolated from a sediment of drainage ditch in winery.

A Gram-stain-negative, motile (by single polar flagellum) and rod-shaped bacterium, designated W1-6T, was isolated from a sediment of drainage ditch in winery in Guiyang, south-western China. Strain W1-6T showed the highest 16S rRNA gene sequence similarities with the type strain of Acidovorax wautersii (98.1%) and Simplicispira lacusdiani (97.9%). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain W1-6T was placed adjacent to the members of the genus Simplicispira and formed a separat subclade. Cells showed oxidase and catalase negative reactions. The only respiratory quinone detected was ubiquinone-8 (Q-8). Summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0 and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) were predominant cellular fatty acids (> 10%) of strain W1-6T. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and five unidentified phospholipids were found in the polar lipid extraction. The genomic DNA G + C content was 65.6%. Strain W1-6T shared the highest digital DNA-DNA hybridization [dDDH, (27.6%)] and average nucleotide identity [ANI (84.3%)] values with the type strain of S. lacusdiani. The dDDH and ANI values were below the cutoff level (dDDH 70%; ANI 95-96%) for species delineation. The polyphasic characteristics indicated that the strain W1-6T represents a novel species of the genus Simplicispira, for which the name Simplicispira sedimenti sp. nov. is proposed. The type strain is W1-6T (= CGMCC 1.16274T = NBRC 115624T).

Dyella sedimenti sp. nov., Isolated from the Sediment of a Winery.

A Gram-staining negative, aerobic, non-motile and rod-shaped bacterium, designated strain N-S-14T, was isolated from the sediment of a winery in Guiyang, south-western China and subjected to a polyphasic taxonomic characteristics. The cells showed oxidase-negative and catalase-negative reactions. Growth occurred at 5-45 °C (optimum 30 °C), pH 5.0-8.0 (optimum pH 6.0-7.0) and with 0-3% (w/v) NaCl on R2A medium. The major respiratory quinone was ubiquinone-8 (Q-8). The predominant cellular fatty acids (> 10.0%) were identified as iso-C15:0, iso-C17:0 and summed feature 9 (iso-C17:1ω9c or C16:0 10-methyl). The profile of polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminophospholipid, one unidentified aminolipid and one unidentified lipid. The genomic DNA G + C content was 67.5%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain N-S-14T should be affiliated to the genus Dyella and formed a clade with most closely related Dyella solisilvae DHG54T (98.3%) and Dyella halodurans DHOG02T (97.8%). The digital DNA-DNA hybridization values ranged from 17.7 to 27.1% and the ANI values ranged from 75.2 to 84.0% between strain N-S-14T and other members of the genus Dyella, respectively, and thus the results indicated that strain N-S-14T represented a novel genomic species belonging to the genus Dyella. The polyphasic taxonomic characteristics indicated that the strain N-S-14T represent a novel species of the genus Dyella, for which the name Dyella sedimenti sp. nov. (type strain N-S-14T = CGMCC 1.18717T = KCTC 82384T) is proposed.

Nocardioides nematodiphilus sp. nov., isolated from rhizosphere of Arabidopsis thaliana.

An actinobacterial strain, designated R-N-C8T, was isolated from the rhizosphere soil of Arabidopsis thaliana collected in Yunnan Province, south-west China. Based on the results of 16S rRNA gene sequence analysis, strain R-N-C8T had highest similarity to Nocardioides terrae CGMCC 1.7056T (96.5%), Nocardioides opuntiae KCTC 19804T (96.3%) and Nocardioides currus IB-3T (96.1%), and lower than 96.0 % similarity to other members of the genus Nocardioides. Phylogenetic trees based on 16S rRNA gene sequences indicated that strain R-N-C8T formed an isolated branch with N. terrae CGMCC 1.7056T and N. opuntiae KCTC 19804T. The polar lipids contained phosphatidylglycerol, diphosphatidylglycerol, one unidentified phosphoglycolipid and four unidentified phospholipids in the cellular membrane. The major fatty acids were identified as iso-C16 : 0, anteiso-C17 : 0, iso-C17 : 0, summed feature 9 (iso-C17 : 1 ω9c and/or C16 : 0 10-methyl) and iso-C15 : 0. The predominant respiratory quinone was MK-8(H4) and ll-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The genomic DNA G+C content was 70.9 mol%. The orthologous average nucleotide identiy values between N. terrae CGMCC 1.7056T, N. currus IB-3T and strain R-N-C8T were 77.1 and 75.1 %, respectively. DNA-DNA hybridization values between N. terrae CGMCC 1.7056T, N. currus IB-3T and strain R-N-C8T were 20.7 and 19.9 % respectively. Data from phenotypic and genotypic analyses supported that strain R-N-C8T represents a new species of Nocardioides, for which the name Nocardioides nematodiphilus sp. nov. is proposed. The type strain is R-N-C8T (=CGMCC 1.18723T= KCTC 49528T).

Sphingobacterium faecale sp. nov., a 1-aminocyclopropane-1-carboxylate deaminase producing bacterium isolated from camel faeces.

An investigation of the diversity of 1-aminocyclopropane-1-carboxylate deaminase producing bacteria associated with camel faeces revealed the presence of a novel bacterial strain designated C459-1T. It was Gram-stain-negative, short-rod-shaped and non-motile. Strain C459-1T was observed to grow optimally at 35 °C, at pH 7.0 and in the presence of 0 % NaCl on Luria-Bertani agar medium. The cells were found to be positive for catalase and oxidase activities. The major fatty acids (>10 %) were identified as iso-C15 : 0, summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and iso-C17 : 0 3-OH. The predominant menaquinone was MK-7. The major polar lipids consisted of phosphatidylethanolamine, one sphingophospholipid, two unknown aminophospholipids, three unknown glycolipids and five unknown lipids. The genomic DNA G+C content was 40.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain C459-1T was affiliated with the genus Sphingobacterium and had the highest sequence similarity to Sphingobacterium tabacisoli h337T (97.0 %) and Sphingobacterium paucimobilis HER1398T (95.6 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain C459-1T and S. tabacisoli h337T were 83.8 and 33.8 %, respectively. Phenotypic characteristics including enzyme activities and carbon source utilization differentiated strain C459-1T from other Sphingobacterium species. Based on its phenotypic, chemotaxonomic and phylogenetic properties, strain C459-1T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium faecale sp. nov. is proposed, with strain is C459-1T (CGMCC 1.18716T=KCTC 82381T) as the type strain.

Azospirillum tabaci sp. nov., a bacterium isolated from rhizosphere soil of Nicotiana tabacum L.

Strain W712T was isolated from rhizosphere soil of Nicotiana tabacum L. collected from Kunming, south-west China. Cells were Gram-staining negative, aerobic, motile and rod shaped. The isolate grew at 20-45 °C (optimum 30 °C), pH 6.0-8.0 (optimum pH 7.0) and in the presence of up to 3.0% (w/v) NaCl (optimum 1%, w/v). Ubiquinone-10 was the only respiratory quinone type. Polar lipids contained diphosphatidylglycerol, phosphatidylmehtylethanolamine, phosphatidylglycerol, phosphatidylcholine and an unidentified aminolipid. The major fatty acids were detected as summed feature 8 (C18:1 ω7c or C18:1 ω6c), summed feature 3 (C16:1 ω7c or C16:1 ω6c) and C18:1 2OH. The genomic DNA G + C content was 68.7%. The ANI values were 94.3%, 93.3% and 93.6% between Azospirillum baldaniorum Sp245T, Azospirillum brasilense ATCC 49958T, Azospirillum formosense CC-Nfb-7T and strain W712T, respectively, which were lower than the prokaryotic species delineation threshold of 95.0-96.0%. The digital DNA-DNA hybridization values between A. baldaniorum Sp245T, A. brasilense ATCC 49958T, A. formosense CC-Nfb-7T and strain W712T indicated that the candidate represents a novel genomic species. According to the phenotypic and genotypic characteristics, we propose that strain W712T warrants the assignment to a novel species, for which the name Azospirillum tabaci sp. nov. (type strain W712T = CGMCC 1.18567T = KCTC 82186T) is proposed.

Sphingobacterium lumbrici sp. nov., a novel bacterium isolated from wormcast of Eisenia foetida.

A novel Gram-stain-negative, rod-shaped, non-motile, yellowish bacterium, designated strain 1.3611T, was isolated from the wormcast of Eisenia foetida. The strain grew optimally at 30-37 ℃, at pH 7.0 and with 0-1.0 % (w/v) NaCl. Based on the results of 16S rRNA gene sequence and phylogenetic analyses, strain 1.3611T showed the highest degree of 16S rRNA gene sequence similarity to Sphingobacterium olei HAL-9T (97.0 %), followed by Sphingobacterium alkalisoli Y3L14T (95.8 %). The respiratory quinone of strain 1.3611T was menaquinone-7 (MK-7) and its major cellular fatty acids were iso-C15 : 0 (41.3 %), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c, 22.1 %) and iso-C17 : 0 3-OH (16.2 %). The major polar lipids were sphingophospholipid, phosphatidylethanolamine, four unidentified glycolipids, two unidentified phospholipids and five unidentified polar lipids. The genomic DNA G+C content was 39.0 mol%. The digital DNA-DNA hybridization and average nucleotide identity values between the genomes of strain 1.3611T and S. olei HAL-9T were 37.9 and 88.9 %, respectively. According to the phenotypic and chemotaxonomic phylogenetic results, strain 1.3611T should represent a novel species of the genus Sphingobacterium, for which the name Sphingobacterium lumbrici sp. nov. is proposed, with strain 1.3611T (=KCTC 62980T=CCTCC AB 2018349T) as the type strain.

Chthonobacter rhizosphaerae sp. nov., a bacterium isolated from rhizosphere soil of Citrus sinenesis.

A Gram-staining negative, facultative anaerobic, motile and short rod-shaped bacterium, designated strain yh7-1T, was isolated from rhizosphere soil of Citrus sinenesis collected from the garden of Citrus sinenesis in Ailao Mountain, south-west China. Cells grew at 15-45 °C, pH 5.0-9.0 and were able to tolerate up to 1% (w/v) NaCl on R2A medium. The respiratory lipoquinone was Q-10 and the major cellular fatty acids contained summed feature 8 (C18:1 ω7c or C18:1 ω6c) and C18:0. Polar lipids in the cellular membrane were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and one unidentified aminophospholipid. The genomic DNA G+C content was 69.9 mol%. On basis of 16S rRNA gene sequence analysis, strain yh7-1T showed the highest similarities with Chthonobacter albigriseus KCTC 42450T (97.6%), Mongoliimonas terrestris KCTC 42635T (97.0%) and lower than 97.0% to other species. Phylogenetic trees based on 16S rRNA gene sequences indicated that strain yh7-1T clustered with C. albigriseus KCTC 42450T. The ANI values ranged between 78.1 and 82.7% for C. albigriseus KCTC 42450T, M. terrestris KCTC 42635T and strain yh7-1T, which were lower than the prokaryotic species delineation threshold of 95.0-96.0%. The digital DNA-DNA hybridization values between C. albigriseus KCTC 42450T, M. terrestris KCTC 42635T and strain yh7-1T indicated that the new isolate represents a novel genomic species. According to the phenotypic and genotypic characteristics, strain yh7-1T should belong to the genus Chthonobacter, for which the name Chthonobacter rhizosphaerae sp. nov. (type strain yh7-1T = CGMCC 1.17236T = CCTCC AB 2019258T = KCTC 82185T) is proposed.

Nocardioides stalactiti sp. nov., isolated from a cave stalactite surface.

An aerobic, rod-shaped, Gram-stain-positive, actinobacterial strain, designated 1.0914T, was isolated from a stalactite sample collected from a cave located in Guizhou Province, southwest PR China. Based on 16S rRNA gene sequence analysis, strain 1.0914T shared highest similarities values with Nocardioides pelophilus CGMCC 4.7388T (97.7 %), Nocardioides immobilis CCTCC AB 2017083T (97.5 %) and Nocardioides silvaticus CCTCC AB 2018079T (97.3 %) and values lower than 97.0 % to other members of the genus Nocardioides. Phylogenetic trees based on 16S rRNA gene sequences indicated that strain 1.0914T formed an isolated branch with N. pelophilus CGMCC 4.7388T, N. immobilis CCTCC AB 2017083T and N. silvaticus CCTCC AB 2018079T. The polar lipids contained phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and one unidentified phospholipid in the cellular membrane. The major fatty acids were identified as iso-C16 : 0, C18 : 1 ω9c, C17 : 1 ω8c and C16 : 0. The predominant respiratory quinone was MK-8(H4) and ll-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The genomic DNA G+C content was 71.1 mol%. The orthologous average nucleotide identiy values between N. pelophilus CGMCC 4.7388T, N. immobilis CCTCC AB 2017083T, N. silvaticus CCTCC 2018079T and strain 1.0914T were 82.3, 81.7 and 81.9 % respectively. DNA-DNA hybridization values between N. pelophilus CGMCC 4.7388T, N. immobilis CCTCC AB 2017083T, N. silvaticus CCTCC 2018079T and strain 1.0914T were 25.2, 24.6 and 24.5 % respectively. The phylogenetic, phenotypic and chemotaxonomic data supported the classification of strain 1.0914T as representing a new species of Nocardioides, for which the name Nocardioides stalactiti sp. nov. is proposed. The type strain is 1.0914T (=CCTCC AB 2018266T=KCTC 49243T).

Sphingobacterium cavernae sp. nov., a novel bacterium isolated from soil sampled at Tiandong Cave.

A Gram-stain-negative, non-motile and rod-shaped bacterium, designated strain 5.0403-2T, was isolated from a cave soil sample collected from Tiandong Cave, Guizhou Province, south-west PR China. Cells showed positive oxidase and catalase reactions. The predominant isoprenoid quinone was MK-7. The major fatty acids were identified as iso-C15 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), iso-C17 : 0 3OH and summed feature 9 (iso-C17 : 1 ω9c or C16 : 0 10-methyl). The cellular polar lipids contained phosphatidylethanolamine, one unidentified phospholipid, three unidentified phosphoglycolipids and four unidentified lipids. The genomic DNA G+C content was 36.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 5.0403-2T should be assigned to the genus Sphingobacterium. Results of 16S rRNA gene sequence similarity analysis showed that strain 5.0403-2T was most similar to Sphingobacterium bovisgrunnientis KCTC 52685T (98.7 %), Sphingobacterium composti KCTC 12578T (98.0 %) and Sphingobacterium alimentarium DSM 22362T (97.3 %) and less than 95.0 % similar to other species of the genus Sphingobacterium. The average nucleotide identity values between strain 5.0403-2T and S. bovisgrunnientis KCTC 52685T, S. composti KCTC 12578T and S. alimentarium DSM 22362T were 94.2, 82.3 and 77.2 % respectively. The digitalDNA-DNA hybridization values between strain 5.0403-2T and S. bovisgrunnientis KCTC 52685T, S. composti KCTC 12578T and S. alimentarium DSM 22362T were 68.4, 25.6 and 20.7 %. These results indicated that the isolate represented a novel genomic species. The polyphasic taxonomic characteristics indicated that strain 5.0304-2T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium cavernae sp. nov. (type strain 5.0403-2T=KCTC 62981T=CCTCC AB 2019257T) is proposed.

Lysobacter prati sp. nov., isolated from a plateau meadow sample.

A novel proteobacterial strain designated SYSU H10001T was isolated from a soil sample collected from plateau meadow in Hongyuan county, Sichuan province, south-western China. The taxonomic position of the strain was investigated using a polyphasic approach. On the basis of 16S rRNA gene sequence similarities and phylogenetic analysis, strain SYSU H10001T was most closely related to Lysobacter soli KCTC 22011T (98.6%, sequence similarity) and Lysobacter panacisoli JCM 19212T (98.2%). The prediction result of secondary metabolites based on genome shown that the strain SYSU H10001T contained 3 clusters of bacteriocins, 1 cluster of non-ribosomal peptide synthetase, 1 cluster of type 1 polyketide synthase and 1 cluster of arylpolyene. In addition, the major isoprenoid quinone was Q-8 and the major fatty acids were identified as iso-C15:0, iso-C17:0 and Summed feature 9. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and three unidentified phospholipids. The genomic DNA G + C content of strain SYSU H10001T was 66.5% (genome). On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU H10001T represents a novel species of the genus Lysobacter, for which the name Lysobacter prati sp. nov. is proposed. The type strain is SYSU H10001T (= KCTC 72062T = CGMCC 1.16662T).

Pseudorivibacter rhizosphaerae gen. nov., sp. nov., isolated from rhizosphere soil of Camellia sinensis (L.) O. Ktze and emended description of the genus Rivibacter.

A Gram-stain-negative, facultative anaerobic, motile and straight rod-shaped bacterium, designated strain C1-9T, was isolated from rhizosphere soil of Camellia sinensis (L.) O. Ktze collected from a tea garden in Huize, south-western PR China. Cells were oxidase-positive and catalase-negative. Growth occurred at 20-40 °C and pH 6.0-10.0, with an optimal growth at 30 °C and pH 7.0. The respiratory quinone was detected as ubiquinone-8 (Q-8). The major fatty acids were identified as summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and summed feature 8 (C18 : 1ω7c or C18 : 1ω6c). The cellular polar lipids contained phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, three unidentified phospholipids, two unidentified lipids, one unidentified aminophospholipid and one unidentified aminolipid. The polyamine types were detected as 1,8-diaminooctane and 2-hydroxyputrescine. The genomic DNA G+C content was 68.6 mol%. Based on the results of 16S rRNA gene sequence analysis, strain C1-9T (MF687442) showed highest sequence similarity to Rivibacter subsaxonicus DSM 19570T (97.1 %). The phylogenetic tree based on 16S rRNA gene sequences showed that strain C1-9T clustered close to R. subsaxonicus DSM 19570T, Methylibium petroleiphilum CCTCC AB 2014193T and species belonging to the genera Rhizobacter and Piscinibacter. The phylogenomic tree indicated that strain C1-9T formed a clade with R. subsaxonicus. The average nucleotide identity value was 76.0 % between strain C1-9T and R. subsaxonicus DSM 19570T, which is lower than the prokaryotic species delineation threshold of 95.0-96.0 %. The polyphasic taxonomic characteristics indicated that strain C1-9T represents a novel species of a new genus within the order Burkholderiales, for which the name Pseudorivibacter rhizosphaerae gen. nov., sp. nov. (type strain C1-9T = KCTC 62325T=CGMCC 1.13864T) is proposed.

Luteimonas lumbrici sp. nov., a novel bacterium isolated from wormcast.

A Gram-stain-negative, yellow-green bacterium, designated 1.1416T, was isolated from wormcast of Eisenia foetida. The strain was non-motile, rod-shaped, and grew optimally on NA medium at 30 °C, pH 7.0 and with 0 % (w/v) NaCl. On the basis of the 16S rRNA gene sequence and phylogenetic analysis, 1.1416T showed the highest degree of 16S rRNA gene sequence similarity to Luteimonas arsenica 26-35T (96.2 %), followed by Luteimonas lutimaris G3T (96.1 %). The respiratory quinone of 1.1416T was ubiquinone-8 (Q-8), and its major cellular fatty acids were iso-C15 : 0 (39.8 %), summed feature 9 (iso-C17 : 1 ω9c or C16 : 0 10-methyl) (18.6 %). The major polar lipids of 1.1416T were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and six unidentified phospholipids. The genomic DNA G+C content of 1.1416T was 71.0 mol%. According to the results of the phenotypic and chemotaxonomic phylogenetic analyses, strain 1.1416T represents a novel species of the genus Luteimonas, for which the name Luteimonas lumbrici sp. nov. is proposed, with strain 1.1416T (=KCTC 62979T=CCTCC AB 2018348T) as the type strain.

Asticcacaulis tiandongensis sp. nov., a new member of the genus Asticcacaulis, isolated from a cave soil sample.

A Gram-stain negative, aerobic, motile and rod-shaped bacterium, designated strain 3.1105T, was isolated from a karst district soil sample collected from Tiandong cave, Guizhou province, south-west PR China. The isolate grew at 10-40 °C and pH 5.0-8.0 and tolerated up to 1 % NaCl (w/v) on R2A medium, with optimal growth at 25-30 °C, pH 7.0 and 0 % NaCl (w/v). Cells showed oxidase-positive and catalase-positive reactions. The respiratory quinone was Q-10. The predominant cellular fatty acids contained C18 : 1ω7c 11-methyl, summed feature 8 (C18 : 1ω7c or C18 : 1ω6c), C16 : 0 and C17 : 0. The major polar lipids were phosphatidylglycerol and monoglycosyldiglycerides. The genomic DNA G+C content was 56.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that 3.1105T should be affiliated to the genus Asticcacaulis and showed highest 16S rRNA gene sequence similarity values with Asticcacaulis excentricus CB 48T (96.0 %), Asticcacaulis endophyticus ZFGT-14T (95.3 %) and lower than 95.3 % similarity to other species of the genus Asticcacaulis. The polyphasic taxonomic characteristics indicated that strain 3.1105T represents a novel species of the genus Asticcacaulis, for which the name Asticcacaulis tiandongensis sp. nov., (type strain 3.1105T=KCTC 62978T=CCTCC AB 2018268T) is proposed.

Aquabacter cavernae sp. nov., a bacterium isolated from cave soil.

A Gram-stain-negative, rod-shaped, non-motile, aerobic, catalase-negative and oxidase-positive bacterium, designated strain Sn-9-2T, was isolated from a cave soil sample collected from Tiandong cave, Guizhou Province, south-west PR China. Growth occurred at 15-40 °C (optimum, 30 °C), at pH 5.0-9.0 (optimum, pH 7.0-8.0) and with 0-1 % NaCl (w/v). The predominant respiration quinone was ubiquinone-10 (Q-10). The major cellular fatty acids were summed feature 8 (C18 : 1ω7c or C18 : 1ω6c; 83.9 %) and C16 : 0 (5.8 %). The major polar lipids were phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, phosphatidylglycerol, three unidentified phospholipids, two unidentified glycolipids, two unidentified polar lipids and one unidentified aminolipid. The DNA G+C content of strain Sn-9-2T was 67.5 mol%. Based on the results of 16S rRNA gene sequence analysis, the nearest phylogenetic neighbours of strain Sn-9-2T (MF958452) were identified as Aquabacter spiritensis (FR733686) DSM 9035T (97.5 %), Xanthobacter autorophicus (jgi.1053054) DSM 432T (97.2 %) and Xanthobacter tagetidis ATCC 700314T RCTF01000015 (96.9 %). The average nucleotide identity values were 78.0, 77.4 and 77.6 % and the digital DNA-DNA hybridization values were 21.8, 22.0 and 18.8 % between strain Sn-9-2T and A. spiritensis DSM 9035T, X. autotrophicus DSM 432T and X. tagetidis DSM 11105T, respectively. The DNA-DNA hybridization data indicated that strain Sn-9-2T represented a novel genomic species. On the basis of the results of phylogenetic analysis, chemotaxonomic data, physiological characteristics and DNA-DNA hybridization data, strain Sn-9-2T should represent a novel species of the genus Aquabacter, for which the name Aquabactercavernae sp. nov. is proposed. The type strain is Sn-9-2T (=KCTC 62308T=CCTCC AB 2018270T).

Flavisolibacter nicotianae sp. nov., isolated from rhizosphere soil of Nicotiana tabacum L.

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, designated strain X7XT, was isolated from a rhizosphere soil sample of Nicotiana tabacum L. collected from a tobacco factory located in Kunming, south-western China. The cells showed oxidase-positive and catalase-positive reactions. Growth occurred at 20-40 °C and pH 6.0-8.0, with optimal growth at 30 °C and pH 7.0. The predominant respiratory quinone was MK-7. The major fatty acids were identified as iso-C15 : 0, iso-C17 : 0 3OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). The cellular polar lipids contained phosphatidylethanolamine, an unidentified aminophospholipid, two unidentified glycolipids, four unidentified aminolipids and four unidentified lipids. The genomic DNA G+C content was 49.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain X7XT should be affiliated to the genus Flavisolibacter. Results from further analysis showed that strain X7XT had highest 16S rRNA gene sequence similarity to Flavisolibacter metallilatus TX0661T (96.4 %) and 'Flavisolibacter swuensis' SR2-4-2T (96.4 %), followed by other species of the genus Flavisolibacter. The polyphasic taxonomic characteristics indicated that strain X7XT represents a novel species of the genus Flavisolibacter, for which the name Flavisolibacternicotianae sp. nov. (type strain X7XT=KCTC 62326T=CGMCC 16451T) is proposed.

Pseudaminobacter arsenicus sp. nov., an arsenic-resistant bacterium isolated from arsenic-rich aquifers.

An arsenic-resistant strain, CB3T, was isolated from arsenic-rich aquifers at the Jianghan Plain in Hubei, China. Phylogenetic and biochemical analysis suggested that it should represent a new species of the genus Pseudaminobacter in the family Phyllobacteriaceae. The 16S rRNA gene of CB3T shared the highest sequence similarities to those of the type strains Pseudaminobacter defluvii THI 051T (97.8 % identity) and Pseudaminobacter salicylatoxidans BN12T (97.4 %). The DNA-DNA relatedness values of CB3T with respect to strains belonging to the genus Pseudaminobacter were less than 70 %. The fatty acid profile of CB3T consisted of C16 : 0, cyclo-C19 : 0ω8c and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) as major components. The major polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidyldimethylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylethanolamine and diphosphatidylglycerol. The DNA G+C content was 61.4 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain CB3T was distinct from previously described Pseudaminobacter species. Therefore, we propose that strain CB3T represents a novel species of the genus Pseudaminobacter, Pseudaminobacterarsenicus sp. nov., strain CB3T (=CCTCC AB2016116T=KCTC 52625T) is designated as the type strain.

Dyella tabacisoli sp. nov., a bacterium isolated from an arable soil sample of Nicotiana tabacum L.

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, designated strain L4-6T, was isolated from an arable soil sample of tobacco in Huize, south-western China and subjected to polyphasic taxonomic characterization. The cells showed oxidase-positive and catalase-positive reactions. Growth occurred at 20-35 °C, at pH 5.0-8.0 and with 0-2 % (w/v) NaCl, optimally at 30 °C, pH 6.0-7.0 and 0-1 % (w/v) NaCl. The major respiratory lipoquinone was ubiquinone-8. The predominant cellular fatty acids (>10.0 %) were identified as summed feature 9 (iso-C17 : 1ω9c or C16 : 0 10-methyl), iso-C15 : 0 and iso-C17 : 0. The polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids, two unidentified aminophospholipids and five unidentified aminolipids. The genomic DNA G+C content was 60.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain L4-6T should be affiliated to the genus Dyella and formed a clade with the most closely related organism Dyella soli JS12-10T. 16S rRNA gene sequences similarity analysis showed that strain L4-6T was mostly closely related to D. soli JS12-10T (98.73 %) and Dyella lipolytica DHOB07T (98.02 %). DNA-DNA hybridization data indicated that strain L4-6T represented a novel genomic species belonging to the genus Dyella. The polyphasic taxonomic characteristics indicated that the strain L4-6T represents a novel species of the genus Dyella, for which the name Dyellatabacisoli sp. nov. (type strain L4-6T=CGMCC 1.16273T=KCTC 62035T) is proposed.

Lysobacter tabacisoli sp. nov., isolated from rhizosphere soil of Nicotiana tabacum L.

A Gram-stain-negative, aerobic, rod-shaped bacterium, designated strain C8-1T, was isolated from the rhizosphere soil of Nicotiana tabacum L. collected from Kunming, south-west China. The cells showed oxidase-positive and catalase-positive reactions. Growth was observed at 10-40 °C, at pH 6.0-8.0 and in the presence of up to 1 % (w/v) NaCl, with optimal growth at 30 °C and pH 7.0. The predominant isoprenoid quinone was Q-8. The major fatty acids were identified as iso-C15 : 0, iso-C17 : 0 and iso-C17 : 1ω9c. The cellular polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, five unidentified phospholipids and two unidentified aminophospholipids. The genomic DNA G+C content was 70.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain C8-1T should be assigned to the genus Lysobacter. 16S rRNA gene sequence similarity analysis showed that strain C8-1T was closely related to Lysobacter cavernae YIM C01544T (98.6 %), Lysobacter soli DCY21T (97.6 %), Lysobacter panacisoli CJ29T (97.3 %), Lysobacter firmicutimachus PB-6250T (97.3 %), Lysobacter niastensis GH41-7T (97.3 %) and Lysobacter gummosus KCTC 12132T (97.1 %). DNA-DNA hybridization data indicated that the isolate may represent a novel genomic species belonging to the genus Lysobacter. Polyphasic taxonomic characteristics indicated that strain C8-1T represents a novel species of the genus Lysobacter, for which the name Lysobacter tabacisoli sp. nov. is proposed. The type strain is C8-1T (=KCTC 62034T=CGMCC 1.16271T) .

Sphingomonas tabacisoli sp. nov., a member of the genus Sphingomonas, isolated from rhizosphere soil of Nicotiana tabacum L.

A Gram-staining-negative, aerobic, motile and rod-shaped bacterium, designated strain X1-8T, was isolated from rhizosphere soil of Nicotiana tabacum L. collected from the tobacco produce base located in Kunming, south-west PR China. Cells showed oxidase-negative and catalase-positive reactions and were motile by means of peritrichous flagella. Growth occurred at 25-40 °C and pH 6.0-8.0 with optimal growth at 30-35 °C, pH 7.0. The major respiratory lipoquinone was Q-10. C16 : 0 and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) were identified as major cellular fatty acids. The profile of polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, sphingoglycolipid, phosphatidylcholine and one unidentified glycolipid. The major polyamine was sym-homospermidine. The genomic DNA G+C content was 66.5 mol%. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that X1-8T should be affiliated to the genus Sphingomonasand formed a clade with most closely related species Sphingomonas changbaiensisNBRC 104936T. The results of 16S rRNA gene sequences similarity analysis indicated that X1-8T had the highest similarity with S. changbaiensisNBRC 104936T (98.4 %) and lower than 96.0 % with other species of the genus Sphingomonas. DNA-DNA hybridization data indicated that X1-8T represented a novel genomic species of the genus Sphingomonas. The characteristics determined in the polyphasic taxonomic study indicated that X1-8T represents a novel species of the genus Sphingomonas, for which the name Sphingomonas tabacisoli sp. nov. (type strain X1-8T=KCTC 62032T=CGMCC 1.16275T) is proposed.

Effect of nicotine from tobacco root exudates on chemotaxis, growth, biocontrol efficiency, and colonization by Pseudomonas aeruginosa NXHG29.

Accumulated evidence suggests that root exudates have a major role in mediating plant-microbe interactions in the rhizosphere. Here, we characterized tobacco root exudates (TREs) by GC-MS and nicotine, scopoletin, and octadecane were identified as three main components of TREs. Qualitative and quantitative chemotaxis assays revealed that Pseudomonas aeruginosa NXHG29 with antagonistic activity displayed positive chemotactic responses towards TREs and their three main components (nicotine, scopoletin, octadecane) and its enhanced chemotaxis were induced by these substances in a concentration-dependent manner. Furthermore, following GC-MS and chemotaxis analysis, nicotine was selected as the target for evaluation of the effect on NXHG29 regarding antagonism, growth, root colonization and biocontrol efficiency. Results of in vitro studies showed that nicotine as a sole carbon source could enhance growth of NXHG29 and significantly increased the antagonism of NXHG29. We also demonstrated that nicotine exerted enhancing effects on the colonization ability of NXHG29 on tobacco roots by combining CLSM observations with investigation of population level dynamics by selective dilution plating method. Results from greenhouse experiments suggested nicotine exhibited stimulatory effects on the biocontrol efficiency of NXHG29 against bacterial wilt and black shank on tobacco. The stimulatory effect of nicotine was affected by the concentration and timing of nicotine application and further supported by the results of population level of NXHG29 on tobacco roots. This is the first report on the enhancement effect of nicotine from TREs on an antagonistic bacterium for its root colonization, control of soil-borne pathogens, regarding the chemotaxis and in vitro antagonism and growth.