scholarly journals Sphingomonas daechungensis sp. nov., isolated from sediment of a eutrophic reservoir

2014 ◽  
Vol 64 (Pt_4) ◽  
pp. 1412-1418 ◽  
Author(s):  
Hangsak Huy ◽  
Long Jin ◽  
Keun Chul Lee ◽  
Song-Gun Kim ◽  
Jung-Sook Lee ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Sequence Data ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Aerobic Bacterium ◽  
Content Type ◽  
Link Type ◽  
Bacterium Strain

Strain CH15-11T, isolated from a sediment sample taken from Daechung Reservoir, South Korea, during the late-blooming period of cyanobacteria, was found to be a Gram-stain-negative, non-motile, non-spore-forming, rod-shaped and aerobic bacterium. Strain CH15-11T grew optimally at pH 7 and 28–30 °C. According to a phylogenetic tree based on 16S rRNA gene sequences, strain CH15-11T belonged to the genus Sphingomonas and clustered with Sphingomonas sediminicola Dae 20T, with which it shared the highest 16S rRNA gene sequence similarity (97.6 %). Chemotaxonomic analysis showed that strain CH15-11T had characteristics typical of members of the genus Sphingomonas , such as the presence of sphingoglycolipid, ubiquinone Q-10 and sym-homospermidine. Plus, strain CH15-11T included summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0 as the major fatty acids. The genomic DNA G+C content was 65.6 mol%. Sequence data showed that strain CH15-11T was most closely related to Sphingomonas sediminicola Dae 20T (97.6 %), Sphingomonas ginsengisoli Gsoil 634T (97.2 %) and Sphingomonas jaspi TDMA-16T (97.0 %). However, the DNA–DNA relatedness values between strain CH15-11T and the most closely related type strains were within a range of 35–59 %. Thus, based on the phylogenetic, phenotypic and genetic data, strain CH15-11T was classified as a member of the genus Sphingomonas as a representative of a novel species, for which the name Sphingomonas daechungensis sp. nov. is proposed. The type strain is CH15-11T ( = KCTC 23718T = JCM 17887T).

scholarly journals Noviherbaspirillum suwonense sp. nov., isolated from an air sample

2014 ◽  
Vol 64 (Pt_5) ◽  
pp. 1552-1558 ◽  
Author(s):  
Soo-Jin Kim ◽  
Ji-Young Moon ◽  
Hang-Yeon Weon ◽  
Seung-Beom Hong ◽  
Soon-Ja Seok ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
The Novel ◽  
Content Type ◽  
Link Type ◽  
Air Sample ◽  
Bacterium Strain

A Gram-stain-negative bacterium, strain 5410S-62T, was isolated from an air sample collected in Suwon, Republic of Korea. It was aerobic, motile, mesophilic and formed rod-shaped cells. Colonies on R2A agar were convex, circular and pale orange with entire margins. Growth occurred at pH 5–9 (optimally at pH 7) and at 10–40 °C (optimally at 28 °C). It did not grow in the presence of 1 % NaCl. Comparative analyses of 16S rRNA gene sequences demonstrated that the novel strain was closely related to members of the genus Noviherbaspirillum . Strain 5410S-62T showed the highest sequence similarity (98.2 %) to Glaciimonas singularis A2-57T. It also showed high 16S rRNA gene sequence similarity (98.1–95.6 %) to members of the genus Noviherbaspirillum (98.1 % to Noviherbaspirillum aurantiacum SUEMI08T, 97.8 % to Noviherbaspirillum soli SUEMI10T and Noviherbaspirillum canariense SUEMI03T, 97.6 % to Noviherbaspirillum psychrotolerans PB1T and 95.6 % to Noviherbaspirillum malthae CC-AFH3T). The strain contained summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0 and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) as major fatty acids, Q-8 as the only ubiquinone and large amounts of phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. Strain 5410S-62T revealed less than 70 % DNA–DNA relatedness with the type strains of closely related species of the genera Noviherbaspirillum and Herbaspirillum and Glaciimonas singularis . Based on the physiological, biochemical and chemotaxonomic data obtained in this study, it is proposed that strain 5410S-62T represents a novel species, Noviherbaspirillum suwonense sp. nov., with 5410S-62T ( = KACC 16657T =  NBRC 108944T) as the type strain.

scholarly journals Faecalicoccus acidiformans gen. nov., sp. nov., isolated from the chicken caecum, and reclassification of Streptococcus pleomorphus (Barnes et al. 1977), Eubacterium biforme (Eggerth 1935) and Eubacterium cylindroides (Cato et al. 1974) as Faecalicoccus pleomorphus comb. nov., Holdemanella biformis gen. nov., comb. nov. and Faecalitalea cylindroides gen. nov., comb. nov., respectively, within the family Erysipelotrichaceae

2014 ◽  
Vol 64 (Pt_11) ◽  
pp. 3877-3884 ◽  
Author(s):  
Celine De Maesschalck ◽  
Filip Van Immerseel ◽  
Venessa Eeckhaut ◽  
Siegrid De Baere ◽  
Margo Cnockaert ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Gene Sequence ◽  
Sequence Similarity ◽  
16S Rrna Gene Sequence ◽  
Rrna Gene ◽  
Rrna Gene Sequence ◽  
Content Type ◽  
Link Type

Strains LMG 27428T and LMG 27427 were isolated from the caecal content of a chicken and produced butyric, lactic and formic acids as major metabolic end products. The genomic DNA G+C contents of strains LMG 27428T and LMG 27427 were 40.4 and 38.8 mol%. On the basis of 16S rRNA gene sequence similarity, both strains were most closely related to the generically misclassified Streptococcus pleomorphus ATCC 29734T. Strain LMG 27428T could be distinguished from S. pleomorphus ATCC 29734T based on production of more lactic acid and less formic acid in M2GSC medium, a higher DNA G+C content and the absence of activities of acid phosphatase and leucine, arginine, leucyl glycine, pyroglutamic acid, glycine and histidine arylamidases, while strain LMG 27428 was biochemically indistinguishable from S. pleomorphus ATCC 29734T. The novel genus Faecalicoccus gen. nov. within the family Erysipelotrichaceae is proposed to accommodate strains LMG 27428T and LMG 27427. Strain LMG 27428T ( = DSM 26963T) is the type strain of Faecalicoccus acidiformans sp. nov., and strain LMG 27427 ( = DSM 26962) is a strain of Faecalicoccus pleomorphus comb. nov. (type strain LMG 17756T = ATCC 29734T = DSM 20574T). Furthermore, the nearest phylogenetic neighbours of the genus Faecalicoccus are the generically misclassified Eubacterium cylindroides DSM 3983T (94.4 % 16S rRNA gene sequence similarity to strain LMG 27428T) and Eubacterium biforme DSM 3989T (92.7 % 16S rRNA gene sequence similarity to strain LMG 27428T). We present genotypic and phenotypic data that allow the differentiation of each of these taxa and propose to reclassify these generically misnamed species of the genus Eubacterium formally as Faecalitalea cylindroides gen. nov., comb. nov. and Holdemanella biformis gen. nov., comb. nov., respectively. The type strain of Faecalitalea cylindroides is DSM 3983T = ATCC 27803T = JCM 10261T and that of Holdemanella biformis is DSM 3989T = ATCC 27806T = CCUG 28091T.

scholarly journals Pseudoseohaeicola caenipelagi gen. nov., sp. nov., isolated from a tidal flat

2015 ◽  
Vol 65 (Pt_6) ◽  
pp. 1819-1824 ◽  
Author(s):  
Sooyeon Park ◽  
Ji-Min Park ◽  
Chul-Hyung Kang ◽  
Song-Gun Kim ◽  
Jung-Hoon Yoon
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Tidal Flat ◽  
Type Strain ◽  
Type Species ◽  
Phylogenetic Trees ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type

A Gram-stain-negative, non-motile, aerobic and pleomorphic bacterium, designated BS-W13T, was isolated from a tidal flat on the South Sea, South Korea, and its taxonomic position was investigated using a polyphasic approach. Strain BS-W13T grew optimally at 25 °C, at pH 7.0–8.0 and in the presence of 1.0–2.0 % (w/v) NaCl. Neighbour-joining and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences showed that strain BS-W13T clustered with the type strain of Seohaeicola saemankumensis , showing the highest sequence similarity (95.96 %) to this strain. Strain BS-W13T exhibited 16S rRNA gene sequence similarity values of 95.95, 95.91, 95.72 and 95.68 % to the type strains of Sulfitobacter donghicola , Sulfitobacter porphyrae , Sulfitobacter mediterraneus and Roseobacter litoralis , respectively. Strain BS-W13T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c as the major fatty acid. The polar lipid profile of strain BS-W13T, containing phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified lipid as major components, was distinguishable from those of some phylogenetically related taxa. The DNA G+C content of strain BS-W13T was 58.1 mol%. The phylogenetic data and differential chemotaxonomic and other phenotypic properties revealed that strain BS-W13T constitutes a novel genus and species within family Rhodobacteraceae of the class Alphaproteobacteria , for which the name Pseudoseohaeicola caenipelagi gen. nov., sp. nov. is proposed. The type strain is BS-W13T ( = KCTC 42349T = CECT 8724T).

scholarly journals Sphingopyxis italica sp. nov., isolated from Roman catacombs

2013 ◽  
Vol 63 (Pt_7) ◽  
pp. 2565-2569 ◽  
Author(s):  
Cynthia Alias-Villegas ◽  
Valme Jurado ◽  
Leonila Laiz ◽  
Cesareo Saiz-Jimenez
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Sequence Comparisons ◽  
Content Type ◽  
Link Type ◽  
Dna Base ◽  
Physiological Tests

A Gram-stain-negative, aerobic, motile, rod-shaped bacterium, strain SC13E-S71T, was isolated from tuff, volcanic rock, where the Roman catacombs of Saint Callixtus in Rome, Italy, was excavated. Analysis of 16S rRNA gene sequences revealed that strain SC13E-S71T belongs to the genus Sphingopyxis , and that it shows the greatest sequence similarity with Sphingopyxis chilensis DSM 14889T (98.72 %), Sphingopyxis taejonensis DSM 15583T (98.65 %), Sphingopyxis ginsengisoli LMG 23390T (98.16 %), Sphingopyxis panaciterrae KCTC 12580T (98.09 %), Sphingopyxis alaskensis DSM 13593T (98.09 %), Sphingopyxis witflariensis DSM 14551T (98.09 %), Sphingopyxis bauzanensis DSM 22271T (98.02 %), Sphingopyxis granuli KCTC 12209T (97.73 %), Sphingopyxis macrogoltabida KACC 10927T (97.49 %), Sphingopyxis ummariensis DSM 24316T (97.37 %) and Sphingopyxis panaciterrulae KCTC 22112T (97.09 %). The predominant fatty acids were C18 : 1ω7c, summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c), C14 : 0 2-OH and C16 : 0. The predominant menaquinone was MK-10. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and sphingoglycolipid. These chemotaxonomic data are common to members of the genus Sphingopyxis . However, a polyphasic approach using physiological tests, DNA base ratios, DNA–DNA hybridization and 16S rRNA gene sequence comparisons showed that the isolate SC13E-S71T belongs to a novel species within the genus Sphingopyxis , for which the name Sphingopyxis italica sp. nov. is proposed. The type strain is SC13E-S71T ( = DSM 25229T = CECT 8016T).

scholarly journals Prauserella coralliicola sp. nov., isolated from the coral Galaxea fascicularis

2014 ◽  
Vol 64 (Pt_10) ◽  
pp. 3341-3345 ◽  
Author(s):  
Jia-Fa Wu ◽  
Jie Li ◽  
Zhi-Qing You ◽  
Si Zhang
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Polar Lipid ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Polar Lipid Profile ◽  
Content Type ◽  
Galaxea Fascicularis ◽  
Link Type

A novel Gram-stain-positive actinobacterium, designated strain SCSIO 11529T, was isolated from tissues of the stony coral Galaxea fascicularis, and characterized by using a polyphasic approach. The temperature range for growth was 22–50 °C (optimum 28–45 °C), the pH range for growth was 6.0–8.0 (optimum pH 7.0), and the NaCl concentration range for growth was 0–7 % (w/v) NaCl. The polar lipid profile contained diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine and an unknown polar lipid. The predominant menaquinone was MK-9(H4). The major fatty acids (>10 %) were iso-C16 : 0, iso-C17 : 1ω6c, iso-C16 : 1 H and C16 : 1ω7c/iso-C15 : 0 2-OH. The DNA G+C content of strain SCSIO 11529T was 70.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SCSIO 11529T belongs to the genus Prauserella , with the closest neighbours being Prauserella marina MS498T (97.0 % 16S rRNA gene sequence similarity), Prauserella rugosa DSM 43194T (96.4 %) and Prauserella flava YIM 90630T (95.9 %). Based on the evidence of the present study, strain SCSIO 11529T is considered to represent a novel species of the genus Prauserella , for which the name Prauserella coralliicola sp. nov. is proposed. The type strain is SCSIO 11529T ( = DSM 45821T = NBRC 109418T).

Namhaeicola litoreus gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from seawater

2012 ◽  
Vol 62 (Pt_9) ◽  
pp. 2163-2168 ◽  
Author(s):  
Yong-Taek Jung ◽  
Ji-Hoon Kim ◽  
So-Jung Kang ◽  
Tae-Kwang Oh ◽  
Jung-Hoon Yoon
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Sequence Similarity ◽  
Phylogenetic Analyses ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Type Strains

A Gram-staining-negative, non-flagellated, non-gliding and pleomorphic bacterial strain, designated DPG-25T, was isolated from seawater in a seaweed farm in the South Sea in Korea and its taxonomic position was investigated by using a polyphasic approach. Strain DPG-25T grew optimally at 25 °C, at pH 7.0–7.5 and in the presence of 2 % (w/v) NaCl. Flexirubin-type pigments were not produced. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain DPG-25T formed a cluster with the type strains of Actibacter sediminis , Aestuariicola saemankumensis and Lutimonas vermicola . Strain DPG-25T exhibited 16S rRNA gene sequence similarity values of 95.3, 93.1 and 93.6 % to the type strains of Actibacter sediminis , Aestuariicola saemankumensis and L. vermicola , respectively. Strain DPG-25T contained MK-6 as the predominant menaquinone and iso-C15 : 0 and iso-C17 : 0 3-OH as the major fatty acids. The major polar lipids detected in strain DPG-25T were phosphatidylethanolamine and one unidentified lipid. The DNA G+C content was 39.9 mol%. Differential phenotypic properties and the phylogenetic distinctiveness of strain DPG-25T demonstrated that this strain is distinguishable from Actibacter sediminis , Aestuariicola saemankumensis and L. vermicola . On the basis of the data presented here, strain DPG-25T represents a novel species in a novel genus of the family Flavobacteriaceae , for which the name Namhaeicola litoreus gen. nov., sp. nov. is proposed. The type strain of Namhaeicola litoreus is DPG-25T ( = KCTC 23702T  = CCUG 61485T).

scholarly journals Amycolatopsis rhabdoformis sp. nov., an actinomycete isolated from a tropical forest soil

2015 ◽  
Vol 65 (Pt_6) ◽  
pp. 1786-1793 ◽  
Author(s):  
Wallace Rafael Souza ◽  
Rafael Eduardo Silva ◽  
Michael Goodfellow ◽  
Kanungnid Busarakam ◽  
Fernanda Sales Figueiro ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Sequence Similarity ◽  
Gene Tree ◽  
Rrna Gene ◽  
Phenotypic Properties ◽  
Phenotypic Data ◽  
Content Type ◽  
Link Type

Strain SB026T was isolated from Brazilian rainforest soil and its taxonomic position established using data from a polyphasic study. The organism showed a combination of chemotaxonomic and morphological features consistent with its classification in the genus Amycolatopsis and formed a branch in the Amycolatopsis 16S rRNA gene tree together with Amycolatopsis bullii NRRL B-24847T, Amycolatopsis plumensis NRRL B-24324T, Amycolatopsis tolypomycina DSM 44544T and Amycolatopsis vancoresmycina NRRL B-24208T. It was related most closely to A. bullii NRRL B-24847T (99.0 % 16S rRNA gene sequence similarity), but was distinguished from this strain by a low level of DNA–DNA relatedness (~46 %) and discriminatory phenotypic properties. Based on the combined genotypic and phenotypic data, it is proposed that the isolate should be classified in the genus Amycolatopsis as representing a novel species, Amycolatopsis rhabdoformis sp. nov. The type strain is SB026T ( = CBMAI 1694T = CMAA 1285T = NCIMB 14900T).

Thauera humireducens sp. nov., a humus-reducing bacterium isolated from a microbial fuel cell

2013 ◽  
Vol 63 (Pt_3) ◽  
pp. 873-878 ◽  
Author(s):  
Gui-Qin Yang ◽  
Jun Zhang ◽  
Soon-Wo Kwon ◽  
Shun-Gui Zhou ◽  
Lu-Chao Han ◽  
...  
Keyword(s):  
Fuel Cell ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Microbial Fuel Cell ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Biochemical Tests ◽  
Content Type ◽  
Link Type

A Gram-negative, rod-shaped, non-spore-forming bacterium, designated SgZ-1T, was isolated from the anode biofilm of a microbial fuel cell. The strain had the ability to grow under anaerobic condition via the oxidation of various organic compounds coupled to the reduction of anthraquione-2,6-disulfonate (AQDS) to anthrahydroquinone-2,6-disulfonate (AHQDS). Growth occurred in TSB in the presence of 0–5.5 % (w/v) NaCl (optimum 0–1 %), at 10–45 °C (optimum 25–37 °C) and at pH 6.0–10.0 (optimum 8.0–8.5). Based on 16S rRNA gene sequence similarity, strain SgZ-1T belonged to the genus Thauera . The highest level of 16S rRNA gene sequences similarity (96.7 %) was found to be with Thauera aminoaromatica S2 T and Thauera selenatis AXT, and lower values were obtained when compared with other recognized Thauera species. Chemotaxonomic analysis revealed that strain SgZ-1T contained Q-8 as the predominant quinone, and putrescine and 2-hydroxyputrescine as the major polyamines. The major cellular fatty acids (>5 %) were C16 : 1ω6c and/or C16 : 1ω7c (44.6 %), C16 : 0 (18.8 %), and C18 : 1ω6c and/or C18 : 1ω7c (12.7 %). Based on its phenotypic and phylogenetic properties, chemotaxonomic analysis and the results of physiological and biochemical tests, strain SgZ-1T ( = KACC 16524T = CCTCC M 2011497T) was designated the type strain of a novel species of the genus Thauera , for which the name Thauera humireducens sp. nov. was proposed.

scholarly journals Erythrobacter pelagi sp. nov., a member of the family Erythrobacteraceae isolated from the Red Sea

2012 ◽  
Vol 62 (Pt_6) ◽  
pp. 1348-1353 ◽  
Author(s):  
Hui-xian Wu ◽  
Pok Yui Lai ◽  
On On Lee ◽  
Xiao-jian Zhou ◽  
Li Miao ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Red Sea ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Phenotypic Properties ◽  
Content Type ◽  
Link Type ◽  
Type Strains

A novel Gram-negative, aerobic, catalase- and oxidase-positive, non-sporulating, non-motile, rod-shaped bacterium, designated strain UST081027-248T, was isolated from seawater of the Red Sea. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain UST081027-248T fell within the genus Erythrobacter . Levels of 16S rRNA gene sequence similarity between the novel strain and the type strains of Erythrobacter species ranged from 95.3 % (with Erythrobacter gangjinensis ) to 98.2 % (with Erythrobacter citreus ). However, levels of DNA–DNA relatedness between strain UST081027-248T and the type strains of closely related species were below 70 %. Optimal growth of the isolate occurred in the presence of 2.0 % NaCl, at pH 8.0–9.0 and at 28–36 °C. The isolate did not produce bacteriochlorophyll a. The predominant cellular fatty acids were C17 : 1ω6c, summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C15 : 0 2-OH. The genomic DNA G+C content of strain UST081027-248T was 60.4 mol%. Phenotypic properties and phylogenetic distinctiveness clearly indicated that strain UST081027-248T represents a novel species of the genus Erythrobacter , for which the name Erythrobacter pelagi sp. nov. is proposed. The type strain is UST081027-248T ( = JCM 17468T = NRRL 59511T).

Carnobacterium iners sp. nov., a psychrophilic, lactic acid-producing bacterium from the littoral zone of an Antarctic pond

2013 ◽  
Vol 63 (Pt_4) ◽  
pp. 1370-1375 ◽  
Author(s):  
Isabel Snauwaert ◽  
Bart Hoste ◽  
Katrien De Bruyne ◽  
Karolien Peeters ◽  
Luc De Vuyst ◽  
...  
Keyword(s):  
Lactic Acid ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Littoral Zone ◽  
Type Species ◽  
Novel Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type

Two lactic acid-producing, Gram-stain-positive rods were isolated from a microbial mat actively growing in the littoral zone of an Antarctic lake (Forlidas Pond) in the Pensacola mountains and studied using a polyphasic taxonomic approach. The isolates were examined by phylogenetic analysis of the 16S rRNA gene, multilocus sequence analysis of pheS, rpoA and atpA, and biochemical and genotypic characteristics. One strain, designated LMG 26641, belonged to Carnobacterium alterfunditum and the other strain, designated LMG 26642T, could be assigned to a novel species, with Carnobacterium funditum DSM 5970T as its closest phylogenetic neighbour (99.2 % 16S rRNA gene sequence similarity). Carnobacterium iners sp. nov. could be distinguished biochemically from other members of the genus Carnobacterium by the lack of acid production from carbohydrates. DNA–DNA relatedness confirmed that strain LMG 26642T represented a novel species, for which we propose the name Carnobacterium iners sp. nov. (type strain is LMG 26642T  = CCUG 62000T).

Sign in / Sign up

Export Citation Format

Share Document