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July 7, 2019

Complete genomic sequence of Pseudoalteromonas sp. strain SAO4-4, a protease-producing bacterium isolated from seawater of the Atlantic Ocean.

The complete genome of Pseudoalteromonas sp. strain SAO4-4, a protease-producing bacterium from seawater, is composed of two circular chromosomes and one plasmid. This genome sequence will provide a better understanding of the ecological roles of protease-producing bacteria in the degradation of organic matter in marine aquatic environments. Copyright © 2018 Tang et al.


July 7, 2019

Complete genome sequence of the virulent Aeromonas salmonicida subsp. masoucida strain RFAS1.

Here, we report the complete genome sequence of the pathogenic Aeromonas salmonicida subsp. masoucida strain RFAS1, isolated from black rockfish and showing signs of furunculosis. Sequencing with the PacBio platform yielded a circular chromosome of 4,783,004?bp and two plasmids (70,968?bp and 63,563?bp) harboring 4,411, 67, and 71 protein-coding genes, respectively. Copyright © 2018 Kim et al.


July 7, 2019

Complete genome sequence of Melissococcus plutonius DAT561, a strain that shows an unusual growth profile, obtained by PacBio sequencing.

Melissococcus plutonius is the causative agent of European foulbrood, and its isolates were believed to be remarkably genetically homogeneous. However, recent epidemiological and pathogenic studies have shown this pathogen to be more heterogeneous than expected. Herein, we present the whole-genome sequence of M. plutonius DAT561, a representative atypical strain. Copyright © 2018 Okumura et al.


July 7, 2019

Complete genome sequence of Klebsiella quasipneumoniae strain S05, a fouling-causing bacterium isolated from a membrane bioreactor.

We report here the complete genome sequence of Klebsiella quasipneumoniae strain S05, a bacterium capable of producing membrane fouling-causing soluble substances and capable of respiring on oxygen, nitrate, and an anodic electrode. The genomic information of strain S05 should help predict metabolic pathways associated with these unique biological properties of this bacterium. Copyright © 2018 Kitajima et al.


July 7, 2019

Complete genome sequence of Achromobacter spanius type strain DSM 23806T, a pathogen isolated from human blood.

Achromobacter spanius is a newly described, non-fermenting, Gram-negative, coccoid pathogen isolated from human blood. Whole-genome sequencing of the A. spanius type strain was performed to investigate the mechanism of pathogenesis of this strain at a genomic level.The complete genome of A. spanius type strain DSM 23806T was sequenced using single-molecule real-time (SMRT) DNA sequencing.The complete genome of DSM 23806T consists of one circular DNA chromosome of 6425783bp with a G+C content of 64.26%. The entire genome contains 5804 predicted coding sequences (CDS) and 55 tRNAs. Genomic island (GI) analysis showed that this strain encodes several important pathogenesis- and resistance-related genes.These results strongly suggest that GIs provide some fitness advantages in A. spanius type strain DSM 23806T. This report provides an extensive understanding of A. spanius at a genomic level as well as an understanding of the evolution of A. spanius. Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.


July 7, 2019

Complete genome sequence of Lactobacillus paracasei EG9, a strain accelerating free amino acid production during cheese ripening.

Lactobacillus paracasei EG9 is a strain isolated from well-ripened cheese and accelerates free amino acid production during cheese ripening. Its complete genome sequence was determined using the PacBio RS II platform, revealing a single circular chromosome of 2,927,257 bp, a G+C content of 46.59%, and three plasmids. Copyright © 2018 Asahina et al.


July 7, 2019

GtTR: Bayesian estimation of absolute tandem repeat copy number using sequence capture and high throughput sequencing.

Tandem repeats comprise significant proportion of the human genome including coding and regulatory regions. They are highly prone to repeat number variation and nucleotide mutation due to their repetitive and unstable nature, making them a major source of genomic variation between individuals. Despite recent advances in high throughput sequencing, analysis of tandem repeats in the context of complex diseases is still hindered by technical limitations. We report a novel targeted sequencing approach, which allows simultaneous analysis of hundreds of repeats. We developed a Bayesian algorithm, namely – GtTR – which combines information from a reference long-read dataset with a short read counting approach to genotype tandem repeats at population scale. PCR sizing analysis was used for validation.We used a PacBio long-read sequenced sample to generate a reference tandem repeat genotype dataset with on average 13% absolute deviation from PCR sizing results. Using this reference dataset GtTR generated estimates of VNTR copy number with accuracy within 95% high posterior density (HPD) intervals of 68 and 83% for capture sequence data and 200X WGS data respectively, improving to 87 and 94% with use of a PCR reference. We show that the genotype resolution increases as a function of depth, such that the median 95% HPD interval lies within 25, 14, 12 and 8% of the its midpoint copy number value for 30X, 200X WGS, 395X and 800X capture sequence data respectively. We validated nine targets by PCR sizing analysis and genotype estimates from sequencing results correlated well with PCR results.The novel genotyping approach described here presents a new cost-effective method to explore previously unrecognized class of repeat variation in GWAS studies of complex diseases at the population level. Further improvements in accuracy can be obtained by improving accuracy of the reference dataset.


July 7, 2019

HECIL: A Hybrid Error Correction Algorithm for Long Reads with Iterative Learning.

Second-generation DNA sequencing techniques generate short reads that can result in fragmented genome assemblies. Third-generation sequencing platforms mitigate this limitation by producing longer reads that span across complex and repetitive regions. However, the usefulness of such long reads is limited because of high sequencing error rates. To exploit the full potential of these longer reads, it is imperative to correct the underlying errors. We propose HECIL-Hybrid Error Correction with Iterative Learning-a hybrid error correction framework that determines a correction policy for erroneous long reads, based on optimal combinations of decision weights obtained from short read alignments. We demonstrate that HECIL outperforms state-of-the-art error correction algorithms for an overwhelming majority of evaluation metrics on diverse, real-world data sets including E. coli, S. cerevisiae, and the malaria vector mosquito A. funestus. Additionally, we provide an optional avenue of improving the performance of HECIL’s core algorithm by introducing an iterative learning paradigm that enhances the correction policy at each iteration by incorporating knowledge gathered from previous iterations via data-driven confidence metrics assigned to prior corrections.


July 7, 2019

Modular traits of the Rhizobiales root microbiota and their evolutionary relationship with symbiotic Rhizobia.

Rhizobia are a paraphyletic group of soil-borne bacteria that induce nodule organogenesis in legume roots and fix atmospheric nitrogen for plant growth. In non-leguminous plants, species from the Rhizobiales order define a core lineage of the plant microbiota, suggesting additional functional interactions with plant hosts. In this work, genome analyses of 1,314 Rhizobiales isolates along with amplicon studies of the root microbiota reveal the evolutionary history of nitrogen-fixing symbiosis in this bacterial order. Key symbiosis genes were acquired multiple times, and the most recent common ancestor could colonize roots of a broad host range. In addition, root growth promotion is a characteristic trait of Rhizobiales in Arabidopsis thaliana, whereas interference with plant immunity constitutes a separate, strain-specific phenotype of root commensal Alphaproteobacteria. Additional studies with a tripartite gnotobiotic plant system reveal that these traits operate in a modular fashion and thus might be relevant to microbial homeostasis in healthy roots. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.


July 7, 2019

Comparative analysis of core genome MLST and SNP typing within a European Salmonella serovar Enteritidis outbreak.

Multi-country outbreaks of foodborne bacterial disease present challenges in their detection, tracking, and notification. As food is increasingly distributed across borders, such outbreaks are becoming more common. This increases the need for high-resolution, accessible, and replicable isolate typing schemes. Here we evaluate a core genome multilocus typing (cgMLST) scheme for the high-resolution reproducible typing of Salmonella enterica (S. enterica) isolates, by its application to a large European outbreak of S. enterica serovar Enteritidis. This outbreak had been extensively characterised using single nucleotide polymorphism (SNP)-based approaches. The cgMLST analysis was congruent with the original SNP-based analysis, the epidemiological data, and whole genome MLST (wgMLST) analysis. Combination of the cgMLST and epidemiological data confirmed that the genetic diversity among the isolates predated the outbreak, and was likely present at the infection source. There was consequently no link between country of isolation and genetic diversity, but the cgMLST clusters were congruent with date of isolation. Furthermore, comparison with publicly available Enteritidis isolate data demonstrated that the cgMLST scheme presented is highly scalable, enabling outbreaks to be contextualised within the Salmonella genus. The cgMLST scheme is therefore shown to be a standardised and scalable typing method, which allows Salmonella outbreaks to be analysed and compared across laboratories and jurisdictions. Copyright © 2018. Published by Elsevier B.V.


July 7, 2019

First description of novel arginine catabolic mobile elements (ACMEs) types IV and V harboring a kdp operon in Staphylococcus epidermidis characterized by whole genome sequencing.

The arginine catabolic mobile element (ACME) was first described in the methicillin-resistant Staphylococcus aureus strain USA300 and is thought to facilitate survival on skin. To date three distinct ACME types have been characterized comprehensively in S. aureus and/or Staphylococcus epidermidis. Type I harbors the arc and opp3 operons encoding an arginine deaminase pathway and an oligopeptide permease ABC transporter, respectively, type II harbors the arc operon only, and type III harbors the opp3 operon only. To investigate the diversity and detailed genetic organization of ACME, whole genome sequencing (WGS) was performed on 32 ACME-harboring oro-nasal S. epidermidis isolates using MiSeq- and PacBio-based WGS platforms. In nine isolates the ACMEs lacked the opp3 operon, but harbored a complete kdp operon (kdpE/D/A/B/C) located a maximum of 2.8?kb upstream of the arc operon. The kdp operon exhibited 63% DNA sequence identity to the native S. aureus kdp operon. These findings identified a novel, previously undescribed ACME type (designated ACME IV), which could be subtyped (IVa and IVb) based on distinct 5′ flanking direct repeat sequences (DRs). Multilocus sequence typing (MLST) sequences extracted from the WGS data identified the sequence types (STs) of the isolates investigated. Four of the nine ACME IV isolates belonged to ST153, and one to ST17, a single locus variant of ST153. A tenth isolate, identified as ST5, harbored another novel ACME type (designated ACME V) containing the kdp, arc and opp3 operons and flanked by DR_F, and DR_B but lacked any internal DRs. ACME V was colocated with a staphylococcal chromosome cassette mec (SCCmec) IV element and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) in a 116.9?kb composite island. The extensive genetic diversity of ACME in S. epidermidis has been further elucidated by WGS, revealing two novel ACME types IV and V for the first time. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.


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