scholarly journals TaxaSE: Exploiting evolutionary conservation within 16S rDNA sequences for enhanced taxonomic annotation

2017 ◽  
Author(s):  
Ali Z Ijaz ◽  
Thomas Jeffries ◽  
Christopher Quince ◽  
Kelly Hamonts ◽  
Brajesh Singh
Keyword(s):  
16S Rdna ◽  
Sequence Similarity ◽  
Marker Gene ◽  
Evolutionary Conservation ◽  
Rrna Gene ◽  
Similarity Metric ◽  
Rdna Sequences ◽  
Fine Grain ◽  
16S Rdna Sequences ◽  
Taxonomic Annotation

Amplicon based taxonomic analysis, which determines the presence of microbial taxa in different environments on the basis of marker gene annotations, often uses percentage identity as the main metric to determine sequence similarity against databases. These data are then used to study the distribution of biodiversity as well as response of microbial communities to environmental conditions. However the 16S rRNA gene displays varying degrees of sequence conservation along its length and percentage identity does not fully utilize this information. Additionally, the prevalent usage of Operational Taxonomic Unit, or OTUs is not without its own issues and may lead to a reduction in annotation capability of the system. Hence a novel approach to taxonomic annotation is needed. Here we introduce a new taxonomic annotation pipeline, TaxaSE, which utilizes Shannon entropy to quantify evolutionary conservation within 16S rDNA sequences for enhanced taxonomic annotations. Furthermore, the system is capable of annotation of individual sequences in order to improve fine grain taxonomic annotations. We present both in-silico comparison of the new similarity metric with percentage identity, as well as comparison with the popular QIIME pipeline. The results demonstrate the new similarity metric achieves better performance especially at lower taxa levels. Furthermore, the pipeline is able to extract more fine grain taxonomic annotations compared to QIIME. These exhibit not only the effectiveness of the new pipeline but also highlight the need to shift away from both percentage identity and OTU based approaches for ecological projects.

scholarly journals TaxaSE: Exploiting evolutionary conservation within 16S rDNA sequences for enhanced taxonomic annotation

2017 ◽  
Author(s):  
Ali Z Ijaz ◽  
Thomas Jeffries ◽  
Christopher Quince ◽  
Kelly Hamonts ◽  
Brajesh Singh
Keyword(s):  
16S Rdna ◽  
Sequence Similarity ◽  
Marker Gene ◽  
Evolutionary Conservation ◽  
Rrna Gene ◽  
Similarity Metric ◽  
Rdna Sequences ◽  
Fine Grain ◽  
16S Rdna Sequences ◽  
Taxonomic Annotation

Amplicon based taxonomic analysis, which determines the presence of microbial taxa in different environments on the basis of marker gene annotations, often uses percentage identity as the main metric to determine sequence similarity against databases. These data are then used to study the distribution of biodiversity as well as response of microbial communities to environmental conditions. However the 16S rRNA gene displays varying degrees of sequence conservation along its length and percentage identity does not fully utilize this information. Additionally, the prevalent usage of Operational Taxonomic Unit, or OTUs is not without its own issues and may lead to a reduction in annotation capability of the system. Hence a novel approach to taxonomic annotation is needed. Here we introduce a new taxonomic annotation pipeline, TaxaSE, which utilizes Shannon entropy to quantify evolutionary conservation within 16S rDNA sequences for enhanced taxonomic annotations. Furthermore, the system is capable of annotation of individual sequences in order to improve fine grain taxonomic annotations. We present both in-silico comparison of the new similarity metric with percentage identity, as well as comparison with the popular QIIME pipeline. The results demonstrate the new similarity metric achieves better performance especially at lower taxa levels. Furthermore, the pipeline is able to extract more fine grain taxonomic annotations compared to QIIME. These exhibit not only the effectiveness of the new pipeline but also highlight the need to shift away from both percentage identity and OTU based approaches for ecological projects.

Human intestinal spirochetosis diagnosed with colonoscopy and analysis of partial 16S rDNA sequences of involved spirochetes

2001 ◽  
Vol 2 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Wolfgang Kraatz ◽  
Ulf Thunberg ◽  
Bertil Pettersson ◽  
Claes Fellström
Keyword(s):  
16S Rdna ◽  
Type Strain ◽  
Sequence Similarity ◽  
Rdna Sequences ◽  
Intestinal Spirochetosis ◽  
16S Rdna Sequences ◽  
Pcr Products ◽  
Human Intestinal Spirochetosis ◽  
Type Strains ◽  
Rrna Sequences

AbstractDNA was extracted from colonic biopsies of 33 patients with and three without evidence of intestinal spirochetosis (IS) in the large bowel. The biopsies were subjected to PCR. A pair of primers, generating a 207 bp fragment, were designed to detect specifically the 16S rDNA gene ofBrachyspira. PCR products of the expected size were obtained from 33 samples with histologic evidence of IS. The PCR amplicons were used for sequencing. The sequences obtained were aligned to the corresponding 16S rRNA sequences of five type strains ofBrachyspira. The sequences of 23 PCR products were 99–100% identical with the correspond-ingB.aalborgitype strain sequence. Two cases showed 99–100% sequence similarity with the type strain ofB.pilosicoliP43/6/78. Six cases could not be referred to any of the known species ofBrachyspira. Two PCR products gave incomplete sequences.

scholarly journals Phenotypic characterization of Astragalus glycyphyllos symbionts and their phylogeny based on the 16S rDNA sequences and RFLP of 16S rRNA gene

2014 ◽  
Vol 105 (6) ◽  
pp. 1033-1048 ◽  
Author(s):  
Sebastian Gnat ◽  
Magdalena Wójcik ◽  
Sylwia Wdowiak-Wróbel ◽  
Michał Kalita ◽  
Aneta Ptaszyńska ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
16S Rdna ◽  
Phenotypic Characterization ◽  
Rrna Gene ◽  
Rdna Sequences ◽  
16S Rdna Sequences ◽  
Astragalus Glycyphyllos Symbionts

Phylogenetic placement of unculturedCeanothusmicrosymbionts using 16S rRNA gene sequences

1999 ◽  
Vol 77 (9) ◽  
pp. 1208-1213 ◽  
Author(s):  
Nancy J Ritchie ◽  
David D Myrold
Keyword(s):  
16S Rdna ◽  
Phylogenetic Trees ◽  
Full Length ◽  
Likelihood Method ◽  
Rrna Gene ◽  
Consensus Sequences ◽  
Rdna Sequences ◽  
16S Rdna Sequences ◽  
Polymerase Chain ◽  
Ceanothus Americanus

Full-length 16S rDNA sequences were amplified directly from the nodules of Ceanothus americanus L. and Ceanothus thyrsiflorus Eschsch. using the polymerase chain reaction. Sequences were determined using an automated sequencer, compared against those in GenBank, and assembled into consensus sequences. The sequences were aligned with other full-length Frankia 16S rDNA sequences available from the data base. Phylogenetic trees were obtained using three different algorithms: neighbor joining, parsimony, and the maximum-likelihood method. All three methods showed that these Ceanothus L. microsymbionts were most closely related to the microsymbiont associated with Dryas drummondii Richardson ex Hook. Lvs. rather than Frankia isolated from the Elaeagnaceae.Key words: Frankia, Ceanothus, 16S rDNA.

Molecular bacterial diversity and distribution in waste from a steel plant

2008 ◽  
Vol 54 (12) ◽  
pp. 996-1005 ◽  
Author(s):  
Dulcecleide B. Freitas ◽  
Mariana P. Reis ◽  
Leandro M. Freitas ◽  
Paulo S. Assis ◽  
Edmar Chartone-Souza ◽  
...  
Keyword(s):  
Bacterial Diversity ◽  
16S Rdna ◽  
Bacterial Communities ◽  
Sequence Similarity ◽  
Diversity Indices ◽  
Operational Taxonomic Units ◽  
Rdna Sequences ◽  
Partial Length ◽  
16S Rdna Sequences ◽  
Novel Taxa

We characterized the bacterial diversity of newly produced steelmaking wastes (NPSW) and steelmaking wastes deposited (SWD) in a restricted land area, generated by the siderurgic industry, using the 16S rDNA clone library approach. A total of 212 partial-length sequences were analyzed, revealing 123 distinct operational taxonomic units (OTUs) determined by the DOTUR program to 97% sequence similarity. Phylogenetic analysis of bacterial 16S rDNA sequences from the NPSW and SWD libraries demonstrated that Gammaproteobacteria, Betaproteobacteria, Alphaproteobacteria, Actinobacteria, Planctomycetes, Firmicutes, and Bacteroidetes were represented in both libraries. Deltaproteobacteria, Acidobacteria, Chloroflexi, Deinococcus-thermus, Gemmatimonadetes, and candidate divisions OP10 and OD1 were only present in the SWD library, and Nitrospira was only present in the NPSW library. The abundance of sequences affiliated with Gammaproteobacteria was high in both libraries. Six previously unclassified OTUs may represent novel taxa. Based on diversity indices (Simpson, Shannon–Weaver, Chao1, and ACE), the SWD library had a higher diversity. LIBSHUFF comparisons of the composition of the 2 libraries showed that they were significantly different. These results indicate that the bacterial communities in steelmaking wastes present high phylogenetic diversity and complexity. A possible association between the functional diversity and the bacterial communities’ complexity requires further phenotypic investigation.

scholarly journals Shewanella gaetbuli sp. nov., a slight halophile isolated from a tidal flat in Korea

2004 ◽  
Vol 54 (2) ◽  
pp. 487-491 ◽  
Author(s):  
Jung-Hoon Yoon ◽  
Kook Hee Kang ◽  
Tae-Kwang Oh ◽  
Yong-Ha Park
Keyword(s):  
16S Rdna ◽  
Tidal Flat ◽  
Sequence Similarity ◽  
Phylogenetic Analyses ◽  
Phenotypic Properties ◽  
16S Rdna Sequence ◽  
Rdna Sequences ◽  
16S Rdna Sequences ◽  
Isoprenoid Quinones ◽  
Type Strains

A Gram-negative, motile, non-spore-forming, rod-shaped strain, TF-27T (=KCCM 41648T=JCM 11814T), was isolated from a tidal flat in Korea. This organism grew well at 25–35 °C, with optimum growth at 30 °C. Strain TF-27T grew optimally in the presence of 2 % NaCl; it did not grow without NaCl or in the presence of >8 % NaCl. Strain TF-27T simultaneously contained both menaquinones and ubiquinones as isoprenoid quinones. The predominant menaquinone was MK-7 and the predominant ubiquinones were Q-7 and Q-8. The major fatty acids in strain TF-27T were iso-C15 : 0 (20·6 %) and iso-C15 : 0 2-OH and/or C16 : 1 ω7c (21·1 %). The DNA G+C content of strain TF-27T was 42 mol%. Phylogenetic analyses based on 16S rDNA sequences showed that strain TF-27T falls within the radiation of the cluster that is encompassed by the genus Shewanella. Levels of 16S rDNA sequence similarity between strain TF-27T and the type strains of Shewanella species were 93·2–96·8 %. On the basis of phenotypic properties and phylogenetic data, strain TF-27T should be placed in the genus Shewanella as a novel species, for which the name Shewanella gaetbuli sp. nov. is proposed.

scholarly journals Herbaspirillum chlorophenolicum sp. nov., a 4-chlorophenol-degrading bacterium

2004 ◽  
Vol 54 (3) ◽  
pp. 851-855 ◽  
Author(s):  
Wan-Taek Im ◽  
Hee-Sung Bae ◽  
Akira Yokota ◽  
Sung Taik Lee
Keyword(s):  
16S Rdna ◽  
Sequence Similarity ◽  
Rdna Sequence ◽  
The Novel ◽  
Comamonas Testosteroni ◽  
16S Rdna Sequence ◽  
Rdna Sequences ◽  
Degrading Bacterium ◽  
16S Rdna Sequences ◽  
Type Strains

A 4-chlorophenol-degrading bacterial strain, formerly designated as a strain of Comamonas testosteroni, was reclassified as a member of the genus Herbaspirillum based on its phenotypic and chemotaxonomic characteristics, as well as phylogenetic analysis using 16S rDNA sequences. Phylogenetic inference based on 16S rDNA sequences showed that strain CPW301T clusters in a phylogenetic branch that contains Herbaspirillum species. 16S rDNA sequence similarity of strain CPW301T to species of the genus Herbaspirillum with validly published names is in the range 98·7–98·9 %. Despite the considerably high 16S rDNA sequence similarity, strain CPW301T could be distinguished clearly from type strains of Herbaspirillum species with validly published names by DNA–DNA relatedness values, which were <15·7 %. The genomic DNA G+C content of strain CPW301T is 61·3 mol%. The predominant ubiquinone is Q-8 and the major cellular fatty acids are C16 : 0 and cyclo-C17 : 0. The strain does not fix nitrogen and is not plant-associated. It is an aerobic rod with one unipolar flagellum. On the basis of these characteristics, a novel Herbaspirillum species, Herbaspirillum chlorophenolicum sp. nov., is proposed. The type strain of the novel species is strain CPW301T (=KCTC 12096T=IAM 15024T).

scholarly journals Phylogenetic Analysis of Nonthermophilic Members of the Kingdom Crenarchaeota and Their Diversity and Abundance in Soils

1998 ◽  
Vol 64 (11) ◽  
pp. 4333-4339 ◽  
Author(s):  
Daniel H. Buckley ◽  
Joseph R. Graber ◽  
Thomas M. Schmidt
Keyword(s):  
16S Rrna ◽  
16S Rdna ◽  
Phylogenetic Analyses ◽  
Pcr Primers ◽  
Soil Samples ◽  
Molecular Techniques ◽  
Rrna Gene ◽  
Rdna Sequences ◽  
16S Rdna Sequences ◽  
Long Term Ecological Research

ABSTRACT Within the last several years, molecular techniques have uncovered numerous 16S rRNA gene (rDNA) sequences which represent a unique and globally distributed lineage of the kingdom Crenarchaeotathat is phylogenetically distinct from currently characterized crenarchaeotal species. rDNA sequences of members of this novel crenarchaeotal group have been recovered from low- to moderate-temperature environments (−1.5 to 32°C), in contrast to the high-temperature environments (temperature, >80°C) required for growth of the currently recognized crenarchaeotal species. We determined the diversity and abundance of the nonthermophilic members of the Crenarchaeota in soil samples taken from cultivated and uncultivated fields located at the Kellogg Biological Station’s Long-Term Ecological Research site (Hickory Corners, Mich.). Clones were generated from 16S rDNA that was amplified by using broad-specificity archaeal PCR primers. Twelve crenarchaeotal sequences were identified, and the phylogenetic relationships between these sequences and previously described crenarchaeotal 16S rDNA sequences were determined. Phylogenetic analyses included nonthermophilic crenarchaeotal sequences found in public databases and revealed that the nonthermophilic Crenarchaeota group is composed of at least four distinct phylogenetic clusters. A 16S rRNA-targeted oligonucleotide probe specific for all known nonthermophilic crenarchaeotal sequences was designed and used to determine their abundance in soil samples. The nonthermophilicCrenarchaeota accounted for as much as 1.42% ± 0.42% of the 16S rRNA in the soils analyzed.

scholarly journals First Report of a Group 16SrI-B Phytoplasma Associated with Gardenia jasminoides in China

Plant Disease ◽  
2012 ◽  
Vol 96 (10) ◽  
pp. 1576-1576 ◽  
Author(s):  
X. C. Sun ◽  
W. J. Zhao
Keyword(s):  
16S Rdna ◽  
Nested Pcr ◽  
Consensus Sequence ◽  
Rrna Gene ◽  
Reference Pattern ◽  
Green Belt ◽  
First Report ◽  
Rdna Sequences ◽  
Gardenia Jasminoides ◽  
16S Rdna Sequences

Gardenia jasminoides J. Ellis, (also known as common gardenia, cape jasmine, or cape jessamine) is a fragrant flowering evergreen tropical plant, a favorite in gardens worldwide. G. jasminoides were found with small, seriously yellowed leaves, stunted growth, and witches'-broom in a green belt on the Southwest University campus in October 2011. The incidence was lower than 2%. In another green belt, G. jasminoides with only slightly yellowing leaves were found. The incidence was about 5%. Five months later, most seriously yellowed leaves withered. However, no withered leaf was observed among the slightly yellowing leaves. Leaf samples from each symptomatic plant, together with asymptomatic plants from the same belt, were collected for total DNA extraction using a modified cetyltrimethylammoniumbromide method (1). The resulting DNA extracts were analyzed by a nested PCR assay using the phytoplasma 16S rRNA gene primer pairs R16mF2/R16mR1 followed by R16F2n/R16R2 (2). DNA fragments of 1.2 kb that corresponded to 16S rDNA were amplified only from the DNA samples of the five plants with the symptoms mentioned above. The purified nested PCR products were cloned in pGEM-T Easy Vector (Promega) and then sequenced. The resulting 16S rDNA sequences were found to be identical (GenBank Accession No. JQ675713). The consensus sequence was analyzed by the iPhyClassifier online tool ( http://plantpathology.ba.ars.usda.gov/cgi-bin/resource/iphyclassifier.cgi ) and found to share 99.4% similarity with the 16S rDNA sequence of the ‘Candidatus Phytoplasma asteris’ reference strain (GenBank Accession No. M30790) that belongs to the 16SrI-B subgroup (3). The virtual RFLP pattern of the G. jasminoides phytoplasma 16S rDNA gene sequence showed maximum similarity to the reference pattern of NC005303 (similarity coefficient of 1.0). The phylogenetic tree based on the 16S rDNA sequences of phytoplasmas belonging to group 16SrI and other distinct phytoplasma groups also showed that our sequences clustered with members of subgroup 16SrI-B. Subsequently, the presence of the phytoplasmas in symptomatic plants was also confirmed by transmission electron microscopy. Taken together, the phytoplasma was classified as a member of subgroup 16SrI-B. To our knowledge, this is the first report of a subgroup 16SrI-B phytoplasma associated with diseased G. jasminoides in China. G. jasminoides yellowing is often considered to result from nutrient deficiency (especially iron compounds). However, our findings showed that a phytoplasma can cause G. jasminoides yellowing, which should be considered in the control of leaves yellowing. References: (1) E. Angelini et al. Vitis 40:79, 2001. (2) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3) Y. Zhao, et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

scholarly journals In Situ Detection of Novel Bacterial Endosymbionts of Acanthamoeba spp. Phylogenetically Related to Members of the Order Rickettsiales

1999 ◽  
Vol 65 (1) ◽  
pp. 206-212 ◽  
Author(s):  
Thomas R. Fritsche ◽  
Matthias Horn ◽  
Seyedreza Seyedirashti ◽  
Romesh K. Gautom ◽  
Karl-Heinz Schleifer ◽  
...  
Keyword(s):  
16S Rdna ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Rrna Gene ◽  
Oligonucleotide Probes ◽  
Gram Negative ◽  
Rdna Sequences ◽  
16S Rdna Sequences ◽  
Bacterial Endosymbionts

ABSTRACT Acanthamoebae are ubiquitous soil and water bactivores which may serve as amplification vehicles for a variety of pathogenic facultative bacteria and as hosts to other, presently uncultured bacterial endosymbionts. The spectrum of uncultured endosymbionts includes gram-negative rods and gram-variable cocci, the latter recently shown to be members of the Chlamydiales. We report here the isolation from corneal scrapings of two Acanthamoebastrains that harbor gram-negative rod endosymbionts that could not be cultured by standard techniques. These bacteria were phylogenetically characterized following amplification and sequencing of the near-full-length 16S rRNA gene. We used two fluorescently labelled oligonucleotide probes targeting signature regions within the retrieved sequences to detect these organisms in situ. Phylogenetic analyses demonstrated that they displayed 99.6% sequence similarity and formed an independent and well-separated lineage within theRickettsiales branch of the alpha subdivision of theProteobacteria. Nearest relatives included members of the genus Rickettsia, with sequence similarities of approximately 85 to 86%, suggesting that these symbionts are representatives of a new genus and, perhaps, family. Distance matrix, parsimony, and maximum-likelihood tree-generating methods all consistently supported deep branching of the 16S rDNA sequences within the Rickettsiales. The oligonucleotide probes displayed at least three mismatches to all other available 16S rDNA sequences, and they both readily permitted the unambiguous detection of rod-shaped bacteria within intact acanthamoebae by confocal laser-scanning microscopy. Considering the long-standing relationship of mostRickettsiales with arthropods, the finding of a related lineage of endosymbionts in protozoan hosts was unexpected and may have implications for the preadaptation and/or recruitment of rickettsia-like bacteria to metazoan hosts.

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