scholarly journals Bacterial population genetics, evolution and epidemiology

1999 ◽  
Vol 354 (1384) ◽  
pp. 701-710 ◽  
Author(s):  
Brian G. Spratt ◽  
Martin C. J. Maiden
Keyword(s):  
Population Structure ◽  
De Novo ◽  
Bacterial Species ◽  
Epidemiological Studies ◽  
Bacterial Isolates ◽  
Bacterial Populations ◽  
Relative Contribution ◽  
Population Structures

Asexual bacterial populations inevitably consist of an assemblage of distinct clonal lineages. However, bacterial populations are not entirely asexual since recombinational exchanges occur, mobilizing small genome segments among lineages and species. The relative contribution of recombination, as opposed to de novo mutation, in the generation of new bacterial genotypes varies among bacterial populations and, as this contribution increases, the clonality of a given population decreases. In consequence, a spectrum of possible population structures exists, with few bacterial species occupying the extremes of highly clonal and completely non–clonal, most containing both clonal and non–clonal elements. The analysis of collections of bacterial isolates, which accurately represent the natural population, by nucleotide sequence determination of multiple housekeeping loci provides data that can be used both to investigate the population structure of bacterial pathogens and for the molecular characterization of bacterial isolates. Understanding the population structure of a given pathogen is important since it impacts on the questions that can be addressed by, and the methods and samples required for, effective molecular epidemiological studies.

scholarly journals Improving the accuracy for Photosystem II and other XFEL structures

2014 ◽  
Vol 70 (a1) ◽  
pp. C571-C571
Author(s):  
Nicholas Sauter ◽  
Aaron Brewster ◽  
Johan Hattne ◽  
Muhamed Amin ◽  
Jan Kern ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
De Novo ◽  
Anomalous Scattering ◽  
Separate Determination ◽  
Structure Factors ◽  
Detector Geometry ◽  
Small Structure ◽  
Image Pixels

Femtosecond-scale XFEL pulses can produce diffraction free from radiation damage, under functional physiological conditions where reaction dynamics can be studied for systems such as photosystem II. However, it has been extremely difficult to derive accurate structure factors from the data since every shot is a still exposure from a distinct specimen. Accuracy can be improved by software methods implemented in the program cctbx.xfel, including optimal indexing and retention of data from multiple lattices, and separate determination of the resolution cutoff for individual lattices. Various techniques can produce well-conforming descriptions of the Bragg spot shape and crystal mosaicity, enabled in part by sub-pixel characterization of the detector geometry. By carefully discriminating between image pixels known to contain diffraction signal and the surrounding pixels containing only background noise, and by extending postrefinement techniques that lead to a better crystal orientation, we derive accurate structure factors with substantially fewer crystal specimen exposures. It is hoped that these developments will make it easier to measure small structure factor differences, such as those from anomalous scattering that will enable the de novo determination of macromolecular structure.

scholarly journals A Statistical Approach for Determination of Disk Diffusion-Based Cutoff Values for Systematic Characterization of Wild-Type and Non-Wild-Type Bacterial Populations in Antimicrobial Susceptibility Testing

2015 ◽  
Vol 53 (6) ◽  
pp. 1812-1822 ◽  
Author(s):  
Giorgia Valsesia ◽  
Malgorzata Roos ◽  
Erik C. Böttger ◽  
Michael Hombach
Keyword(s):  
Resistance Mechanisms ◽  
Beta Lactamase ◽  
Wild Type ◽  
Beta Lactam ◽  
Bacterial Populations ◽  
Content Type ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli

In this study, we introduce a new approach for determination of epidemiologic cutoffs (ECOFFs) and resistant-population cutoffs (RCOFFs) based on receiver operating characteristic (ROC) curves. As an example, the method was applied for determination of ECOFFs for seven different beta-lactam antibiotics and wild-type populations ofEscherichia coli,Klebsiella pneumoniae, andEnterobacter cloacae. In addition, RCOFFs were determined for bacterial populations with defined resistance mechanisms (“resistotypes”), i.e., extended-spectrum beta-lactamase (ESBL)-positiveE. coli, ESBL-positiveK. pneumoniae, and ESBL-positiveE. cloacae; AmpC cephalosporinase-positiveE. coliand AmpC-positiveK. pneumoniae; and broad-spectrum beta-lactamase (BSBL)-positiveE. coli. RCOFFs and ECOFFs are instrumental for a systematic characterization of associations between resistotypes and wild-type populations.

scholarly journals Open Database Searching Enables the Identification and Comparison of Bacterial Glycoproteomes without Defining Glycan Compositions Prior to Searching

2020 ◽  
Vol 19 (9) ◽  
pp. 1561-1574 ◽  
Author(s):  
Ameera Raudah Ahmad Izaham ◽  
Nichollas E. Scott
Keyword(s):  
Bacterial Species ◽  
Low Frequency ◽  
Burkholderia Cenocepacia ◽  
Database Searching ◽  
Modified Peptides ◽  
Fetus Subsp ◽  
Indispensable Tool ◽  
Bacterial Proteomes

Mass spectrometry has become an indispensable tool for the characterization of glycosylation across biological systems. Our ability to generate rich fragmentation of glycopeptides has dramatically improved over the last decade yet our informatic approaches still lag behind. Although glycoproteomic informatics approaches using glycan databases have attracted considerable attention, database independent approaches have not. This has significantly limited high throughput studies of unusual or atypical glycosylation events such as those observed in bacteria. As such, computational approaches to examine bacterial glycosylation and identify chemically diverse glycans are desperately needed. Here we describe the use of wide-tolerance (up to 2000 Da) open searching as a means to rapidly examine bacterial glycoproteomes. We benchmarked this approach using N-linked glycopeptides of Campylobacter fetus subsp. fetus as well as O-linked glycopeptides of Acinetobacter baumannii and Burkholderia cenocepacia revealing glycopeptides modified with a range of glycans can be readily identified without defining the glycan masses before database searching. Using this approach, we demonstrate how wide tolerance searching can be used to compare glycan use across bacterial species by examining the glycoproteomes of eight Burkholderia species (B. pseudomallei; B. multivorans; B. dolosa; B. humptydooensis; B. ubonensis, B. anthina; B. diffusa; B. pseudomultivorans). Finally, we demonstrate how open searching enables the identification of low frequency glycoforms based on shared modified peptides sequences. Combined, these results show that open searching is a robust computational approach for the determination of glycan diversity within bacterial proteomes.

scholarly journals Mucispirillum schaedleri gen. nov., sp. nov., a spiral-shaped bacterium colonizing the mucus layer of the gastrointestinal tract of laboratory rodents

2005 ◽  
Vol 55 (3) ◽  
pp. 1199-1204 ◽  
Author(s):  
Bronwyn R. Robertson ◽  
Jani L. O'Rourke ◽  
Brett A. Neilan ◽  
Peter Vandamme ◽  
Stephen L. W. On ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
New Genus ◽  
Bacterial Species ◽  
Mucus Layer ◽  
Bacterial Isolates ◽  
New Genus And Species ◽  
Laboratory Rodents ◽  
Distinct Lineage ◽  
High Level

The mammalian gastrointestinal tract is covered by a layer of mucus that can harbour a range of bacterial species specifically adapted to colonize this ecological niche. Examination of 110 bacterial isolates cultivated from the gastrointestinal tract of 23 mice revealed the presence of a subgroup of 30 isolates that did not correspond genetically with genera commonly associated with this site, i.e. members of the ε-Proteobacteria such as Helicobacter and Campylobacter species. Instead this group of isolates was found to lie within the phylum Deferribacteres, a completely distinct lineage in the domain Bacteria. There was a high level of consensus in results obtained from the phenotypic and genotypic characterization of a number of the isolates, which showed they were distinct from other members of the Deferribacteres. As such, they are proposed to constitute a new genus and species, Mucispirillum schaedleri gen. nov., sp. nov. These organisms are anaerobic, Gram-negative, spiral-shaped rods with bipolar flagella. The type strain is HRI I17T (=ATCC BAA-1009T=ACM 5223T).

scholarly journals Assessing Genetic Heterogeneity within Bacterial Species Isolated from Gastrointestinal and Environmental Samples: How Many Isolates Does It Take?

2008 ◽  
Vol 74 (11) ◽  
pp. 3490-3496 ◽  
Author(s):  
D. Döpfer ◽  
W. Buist ◽  
Y. Soyer ◽  
M. A. Munoz ◽  
R. N. Zadoks ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Real Life ◽  
Strain Typing ◽  
Bacterial Isolates ◽  
Bacterial Populations ◽  
Laboratory Capacity ◽  
Streptococcus Uberis ◽  
Typing Methods ◽  
Sources Of Infection ◽  
Transmission Pathways

ABSTRACT Strain typing of bacterial isolates is increasingly used to identify sources of infection or product contamination and to elucidate routes of transmission of pathogens or spoilage organisms. Usually, the number of bacterial isolates belonging to the same species that is analyzed per sample is determined by convention, convenience, laboratory capacity, or financial resources. Statistical considerations and knowledge of the heterogeneity of bacterial populations in various sources can be used to determine the number of isolates per sample that is actually needed to address specific research questions. We present data for intestinal Escherichia coli, Listeria monocytogenes, Klebsiella pneumoniae, and Streptococcus uberis from gastrointestinal, fecal, or soil samples characterized by ribotyping, pulsed-field gel electrophoresis, and PCR-based strain-typing methods. In contrast to previous studies, all calculations were performed with a single computer program, employing software that is freely available and with in-depth explanation of the choice and derivation of prior distributions. Also, some of the model assumptions were relaxed to allow analysis of the special case of two (groups of) strains that are observed with different probabilities. Sample size calculations, with a Bayesian method of inference, show that from 2 to 20 isolates per sample need to be characterized to detect all strains that are present in a sample with 95% certainty. Such high numbers of isolates per sample are rarely typed in real life due to financial or logistic constraints. This implies that investigators are not gaining maximal information on strain heterogeneity and that sources and transmission pathways may go undetected.

scholarly journals Identification of a Novel Yersinia enterocolitica Strain from Bats in Association with a Bat Die-Off That Occurred in Georgia (Caucasus)

2020 ◽  
Vol 8 (7) ◽  
pp. 1000
Author(s):  
Tata Imnadze ◽  
Ioseb Natradze ◽  
Ekaterine Zhgenti ◽  
Lile Malania ◽  
Natalia Abazashvili ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Virulence Plasmid ◽  
The Novel ◽  
Wild Animals ◽  
Sequence Analyses ◽  
Enterocolitica Strain ◽  
Distinct Cluster ◽  
Current Report

Yersinia entercolitica is a bacterial species within the genus Yersinia, mostly known as a human enteric pathogen, but also recognized as a zoonotic agent widespread in domestic pigs. Findings of this bacterium in wild animals are very limited. The current report presents results of the identification of cultures of Y. entercolitica from dead bats after a massive bat die-off in a cave in western Georgia. The growth of bacterial colonies morphologically suspected as Yersinia was observed from three intestine tissues of 11 bats belonging to the Miniopterus schreibersii species. These three isolates were identified as Y. enterocolitica based on the API29 assay. No growth of Brucella or Francisella bacteria was observed from tissues of dead bats. Full genomes (a size between 4.6–4.7 Mbp) of the Yersinia strains isolated from bats were analyzed. The phylogenetic sequence analyses of the genomes demonstrated that all strains were nearly identical and formed a distinct cluster with the closest similarity to the environmental isolate O:36/1A. The bat isolates represent low-pathogenicity Biotype 1A strains lacking the genes for the Ail, Yst-a, Ysa, and virulence plasmid pYV, while containing the genes for Inv, YstB, and MyfA. Further characterization of the novel strains cultured from bats can provide a clue for the determination of the pathogenic properties of those strains.

scholarly journals Metaproteomics as a tool for studying the protein landscape of human-gut bacterial species

2021 ◽  
Author(s):  
Moses Stamboulian ◽  
Jamie Canderan ◽  
Yuzhen Ye
Keyword(s):  
Human Health ◽  
Gut Microbiome ◽  
De Novo ◽  
Bacterial Species ◽  
Individual Species ◽  
Human Gut ◽  
Human Gut Microbiome ◽  
Microbial Species ◽  
Microbial Organisms

AbstractHost-microbiome interactions and the microbial community have broad impact in human health and diseases. Most microbiome based studies are performed at the genome level based on next-generation sequencing techniques, but metaproteomics is emerging as a powerful technique to study microbiome functional activity by characterizing the complex and dynamic composition of microbial proteins. We conducted a large-scale survey of human gut microbiome metaproteomic data to identify generalist species that are ubiquitously expressed across all samples and specialists that are highly expressed in a small subset of samples associated with a certain phenotype. We were able to utilize the metaproteomic mass spectrometry data to reveal the protein landscapes of these species, which enables the characterization of the expression levels of proteins of different functions and underlying regulatory mechanisms, such as operons. Finally, we were able to recover a large number of open reading frames (ORFs) with spectral support, which were missed by de novo protein-coding gene predictors. We showed that a majority of the rescued ORFs overlapped with de novo predicted proteincoding genes, but on opposite strands or on different frames. Together, these demonstrate applications of metaproteomics for the characterization of important gut bacterial species. Results are available for public access at https://omics.informatics.indiana.edu/GutBac.Author summaryMany reference genomes for studying human gut microbiome are available, but knowledge about how microbial organisms work is limited. Identification of proteins at individual species or community level provides direct insight into the functionality of microbial organisms. By analyzing more than a thousand metaproteomics datasets, we examined protein landscapes of more than two thousands of microbial species that may be important to human health and diseases. This work demonstrated new applications of metaproteomic datasets for studying individual genomes. We made the analysis results available through the GutBac website, which we believe will become a resource for studying microbial species important for human health and diseases.

scholarly journals Ionome Changes in Xylella fastidiosa–Infected Nicotiana tabacum Correlate With Virulence and Discriminate Between Subspecies of Bacterial Isolates

2014 ◽  
Vol 27 (10) ◽  
pp. 1048-1058 ◽  
Author(s):  
J. E. Oliver ◽  
S. A. Sefick ◽  
J. K. Parker ◽  
T. Arnold ◽  
P. A. Cobine ◽  
...  
Keyword(s):  
Nicotiana Tabacum ◽  
Xylella Fastidiosa ◽  
Nutrient Utilization ◽  
Plant Colonization ◽  
Bacterial Isolates ◽  
Multivariate Statistical ◽  
Bacterial Populations ◽  
Phenotypic Response ◽  
Bacterial Plant Pathogen

Characterization of ionomes has been used to uncover the basis of nutrient utilization and environmental adaptation of plants. Here, ionomic profiles were used to understand the phenotypic response of a plant to infection by genetically diverse isolates of Xylella fastidiosa, a gram-negative, xylem-limited bacterial plant pathogen. In this study, X. fastidiosa isolates were used to infect a common model host (Nicotiana tabacum ‘SR1’), and leaf and sap concentrations of eleven elements together with plant colonization and symptoms were assessed. Multivariate statistical analysis revealed that changes in the ionome were significantly correlated with symptom severity and bacterial populations in host petioles. Moreover, plant ionome modification by infection could be used to differentiate the X. fastidiosa subspecies with which the plant was infected. This report establishes host ionome modification as a phenotypic response to infection.

scholarly journals Characterization of Bacterial Microbiota Composition along the Gastrointestinal Tract in Rabbits

Animals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Elisa Cotozzolo ◽  
Paola Cremonesi ◽  
Giulio Curone ◽  
Laura Menchetti ◽  
Federica Riva ◽  
...  
Keyword(s):  
Digestive Tract ◽  
Large Intestine ◽  
Bacterial Species ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Productive Performance ◽  
Bacterial Populations ◽  
Bacterial Microbiota ◽  
Rrna Gene Sequencing

The microbiota is extremely important for the animal’s health, but, to date, knowledge on the intestinal microbiota of the rabbit is very limited. This study aimed to describe bacterial populations that inhabit the different gastrointestinal compartments of the rabbit: stomach, duodenum, jejunum, ileum, caecum, and colon. Samples of the luminal content from all compartments of 14 healthy New White Zealand rabbits were collected at slaughter and analyzed using next generation 16S rRNA Gene Sequencing. The findings uncovered considerable differences in the taxonomic levels among the regions of the digestive tract. Firmicutes were the most abundant phylum in all of the sections (45.9%), followed by Bacteroidetes in the large intestine (38.9%) and Euryarchaeota in the foregut (25.9%). Four clusters of bacterial populations were observed along the digestive system: (i) stomach, (ii) duodenum and jejunum, (iii) ileum, and (iv) large intestine. Caecum and colon showed the highest richness and diversity in bacterial species, while the highest variability was found in the upper digestive tract. Knowledge of the physiological microbiota of healthy rabbits could be important for preserving the health and welfare of the host as well as for finding strategies to manipulate the gut microbiota in order to also promote productive performance.

scholarly journals Study of an arsenic metabolizing bacteria from arsenic contaminated soil of Chandpur district, Bangladesh

2019 ◽  
Vol 8 (1) ◽  
pp. 57-65
Author(s):  
Roksana Khanam ◽  
Ripa Moni ◽  
Md Zahidul Islam ◽  
Md Morsaline Billah ◽  
Umme Salma Zohora ◽  
...  
Keyword(s):  
Contaminated Soil ◽  
Bacterial Species ◽  
Toxic Metal ◽  
Extracellular Enzyme ◽  
Bacterial Isolates ◽  
Toxic Heavy Metals ◽  
16S Rrna Sequence ◽  
Yeast Extract Mannitol ◽  
16S Rrna Sequence Analysis

Arsenic is a toxic metal found as inorganic oxyanion arsenate As(V) and arsenite As (III) species. The disposal of toxic heavy metals such as arsenic poses high risk to environment. The present study was undertaken to isolate arsenic-metabolizing bacteria from arsenic contaminated soil of Chandpur district, which is one of the most arsenic contaminated area in Bangladesh and later these bacteria were screened for their ability to metabolize arsenate. Out of ninety eight isolates, ten were found to be capable of metabolizing arsenic in Yeast Extract Mannitol (YEM) medium containing 2 mM arsenate at 37ºC. One of the bacterial isolates designated as I-25 was found to produce an extracellular enzyme which can reduce As(V) into As(III) and able to grow in presence of up to 500 mM arsenate. Subsequent molecular identification of this enzyme producing bacterial isolate using 16s rRNA sequence analysis was correlated with previously identified isolate as Bacillus aryabhatti. Further characterization of the enzyme showed that optimum pH of the extracellular enzyme by the bacterial species was 7 and optimum temperature for the enzyme activity was 60ºC. The bacterial isolates can be exploited for the study of possible bioremediation of arsenic contamination. Jahangirnagar University J. Biol. Sci. 8(1): 57-65, 2019 (June)

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