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July 7, 2019

Complete genome sequence of the Clostridium difficile laboratory strain 630¿ erm reveals differences from strain 630, including translocation of the mobile element CTn 5.

Background Clostridium difficile strain 630¿erm is a spontaneous erythromycin sensitive derivative of the reference strain 630 obtained by serial passaging in antibiotic-free media. It is widely used as a defined and tractable C. difficile strain. Though largely similar to the ancestral strain, it demonstrates phenotypic differences that might be the result of underlying genetic changes. Here, we performed a de novo assembly based on single-molecule real-time sequencing and an analysis of major methylation patterns.ResultsIn addition to single nucleotide polymorphisms and various indels, we found that the mobile element CTn5 is present in the gene encoding the methyltransferase rumA rather than adhesin CD1844 where it is located in the reference strain.ConclusionsTogether, the genetic features identified in this study may help to explain at least part of the phenotypic differences. The annotated genome sequence of this lab strain, including the first analysis of major methylation patterns, will be a valuable resource for genetic research on C. difficile.


July 7, 2019

Complete genome sequence of Yersinia ruckeri strain CSF007-82, etiologic agent of red mouth disease in salmonid fish.

We present the complete, closed, and finished chromosomal and extrachromosomal genome sequences of Yersinia ruckeri strain CSF007-82, the etiologic agent of enteric red mouth disease in salmonid fish. The chromosome is 3,799,036 bp with a G+C content of 47.5% and encodes 3,530 predicted coding sequences (CDS), 7 ribosomal operons, and 80 tRNAs. Copyright © 2015 Nelson et al.


July 7, 2019

Complete genome sequence of the fish pathogen Flavobacterium psychrophilum ATCC 49418(T.).

Flavobacterium psychrophilum is the causative agent of bacterial cold water disease and rainbow trout fry mortality syndrome in salmonid fishes and is associated with significant losses in the aquaculture industry. The virulence factors and molecular mechanisms of pathogenesis of F. psychrophilum are poorly understood. Moreover, at the present time, there are no effective vaccines and control using antimicrobial agents is problematic due to growing antimicrobial resistance and the fact that sick fish don’t eat. In the hopes of identifying vaccine and therapeutic targets, we sequenced the genome of the type strain ATCC 49418 which was isolated from the kidney of a Coho salmon (Oncorhychus kisutch) in Washington State (U.S.A.) in 1989. The genome is 2,715,909 bp with a G+C content of 32.75%. It contains 6 rRNA operons, 49 tRNA genes, and is predicted to encode 2,329 proteins.


July 7, 2019

Complete genome sequence of Bifidobacterium adolesentis BBMN23, a probiotic strain from healthy centenarian.

Bifidobacterium adolesentis BBMN23 (CGMCC No. 2264) was a probiotic strain originated from the feces of a centenarian. It is an excellent model for the study of the adaptation of genus bifidobacteria to adult human gut, which is a key factor in bifidobacterial strains that allows them to persist in gut and become useful in the food and medical industries. In the present study the complete genome sequence of BBMN23 is presented to provide insight into this strain. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Analysis of a draft genome sequence of Kitasatospora cheerisanensis KCTC 2395 producing bafilomycin antibiotics.

Kitasatospora cheerisanensis KCTC 2395, producing bafilomycin antibiotics belonging to plecomacrolide group, was isolated from a soil sample at Mt. Jiri, Korea. The draft genome sequence contains 8.04 Mb with 73.6% G+C content and 7,810 open reading frames. All the genes for aerial mycelium and spore formations were confirmed in this draft genome. In phylogenetic analysis of MurE proteins (UDP-N-acetylmuramyl-L-alanyl-D-glutamate:DAP ligase) in a conserved dcw (division of cell wall) locus, MurE proteins of Kitasatospora species were placed in a separate clade between MurEs of Streptomyces species incorporating LL-diaminopimelic acid (DAP) and MurEs of Saccharopolyspora erythraea as well as Mycobacterium tuberculosis ligating meso-DAP. From this finding, it was assumed that Kitasatospora MurEs exhibit the substrate specificity for both LL-DAP and meso-DAP. The bafilomycin biosynthetic gene cluster was located in the left subtelomeric region. In 71.3 kb-long gene cluster, 17 genes probably involved in the biosynthesis of bafilomycin derivatives were deduced, including 5 polyketide synthase (PKS) genes comprised of 12 PKS modules.


July 7, 2019

Gut symbionts from distinct hosts exhibit genotoxic activity via divergent colibactin biosynthetic pathways.

Secondary metabolites produced by nonribosomal peptide synthetase (NRPS) or polyketide synthase (PKS) pathways are chemical mediators of microbial interactions in diverse environments. However, little is known about their distribution, evolution, and functional roles in bacterial symbionts associated with animals. A prominent example is “colibactin”, a largely unknown family of secondary metabolites produced by Escherichia coli via a hybrid NRPS-PKS biosynthetic pathway, inflicting DNA damage upon eukaryotic cells and contributing to colorectal cancer and tumor formation in the mammalian gut. Thus far, homologs of this pathway have only been found in closely related Enterobacteriaceae, while a divergent variant of this gene cluster was recently discovered in a marine alphaproteobacterial Pseudovibrio strain. Herein, we sequenced the genome of Frischella perrara PEB0191, a bacterial gut symbiont of honey bees, and identified a homologous colibactin biosynthetic pathway related to those found in Enterobacteriaceae. We show that the colibactin genomic island (GI) has conserved gene synteny and biosynthetic module architecture across F. perrara, Enterobacteriaceae and the Pseudovibrio strain. Comparative metabolomics analyses of F. perrara and E. coli further reveal that these two bacteria produce related colibactin pathway-dependent metabolites. Finally, we demonstrate that F. perrara, like E. coli, causes DNA damage in eukaryotic cells in vitro in a colibactin pathway-dependent manner. Together, these results support that divergent variants of the colibactin biosynthetic pathway are widely distributed among bacterial symbionts, producing related secondary metabolites and likely endowing its producer with functional capabilities important for diverse symbiotic associations. Copyright © 2014, American Society for Microbiology. All Rights Reserved.


July 7, 2019

Complete sequences of six IncA/C plasmids of multidrug-resistant Salmonella enterica subsp. enterica serotype Newport.

Multidrug-resistant (MDR) Salmonella enterica subsp. enterica serotype Newport has been a long-standing public health concern in the United States. We present the complete sequences of six IncA/C plasmids from animal-derived MDR S. Newport ranging from 80.1 to 158.5 kb. They shared a genetic backbone with S. Newport IncA/C plasmids pSN254 and pAM04528. Copyright © 2015 Cao et al.


July 7, 2019

Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists.

To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergent evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a ‘symbiosis toolkit’, with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.


July 7, 2019

Sequence analysis of Staphylococcus hyicus ATCC 11249T, an etiological agent of exudative epidermitis in swine, reveals a type VII secretion system locus and a novel 116-kilobase genomic island harboring toxin-encoding genes.

Staphylococcus hyicus is the primary etiological agent of exudative epidermitis in swine. Analysis of the complete genome sequence of the type strain revealed a locus encoding a type VII secretion system and a large chromosomal island harboring the genes encoding exfoliative toxin ExhA and an EDIN toxin homolog. Copyright © 2015 Calcutt et al.


July 7, 2019

Do echinoderm genomes measure up?

Echinoderm genome sequences are a corpus of useful information about a clade of animals that serve as research models in fields ranging from marine ecology to cell and developmental biology. Genomic information from echinoids has contributed to insights into the gene interactions that drive the developmental process at the molecular level. Such insights often rely heavily on genomic information and the kinds of questions that can be asked thus depend on the quality of the sequence information. Here we describe the history of echinoderm genomic sequence assembly and present details about the quality of the data obtained. All of the sequence information discussed here is posted on the echinoderm information web system, Echinobase.org. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Short communication: Single molecule, real-time sequencing technology revealed species- and strain-specific methylation patterns of 2 Lactobacillus strains.

Pacific Biosciences’ (Menlo Park, CA) single molecule, real-time sequencing technology was reported to have some advantages in generating finished genomes and characterizing the epigenome of bacteria. In the present study, this technology was used to sequence 2 Lactobacillus strains, Lactobacillus casei Zhang and Lactobacillus plantarum P-8. Previously, the former bacterium was sequenced by an Applied Biosystems 3730 DNA analyzer (Grand Island, NY), whereas the latter one was analyzed with Roche 454 (Indianapolis, IN) and Illumina sequencing technologies (San Diego, CA). The results showed that single molecule, real-time sequencing resulted in high-quality, finished genomes for both strains. Interestingly, epigenome analysis indicates the presence of 1 active N(6)-methyladenine methyltransferase in L. casei Zhang, but none in L. plantarum P-8. Our study revealed for the first time a completely different methylation pattern in 2 Lactobacillus strains. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.


July 7, 2019

Complete genome sequence of Bifidobacterium animalis subsp. lactis A6, a probiotic strain with high acid resistance ability.

Bifidobacterium animalis subsp. lactis A6 (BAA6) (CGMCC No. 9273) was a probiotic strain isolated from the feces of a centenarian. Previous study showed that BAA6 had high acid resistance to low pH which is a critical factor influencing its healthy benefits. Elaborating the stress resistant mechanisms of bifidobacteria is important to extensively exploit this probiotic. Here, we reported the complete genome sequence of BAA6 that contains 1,958,651 bp encoding 1622 CDSs, 16 rRNA genes, 52 tRNA genes. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

micropan: an R-package for microbial pan-genomics.

A pan-genome is defined as the set of all unique gene families found in one or more strains of a prokaryotic species. Due to the extensive within-species diversity in the microbial world, the pan-genome is often many times larger than a single genome. Studies of pan-genomes have become popular due to the easy access to whole-genome sequence data for prokaryotes. A pan-genome study reveals species diversity and gene families that may be of special interest, e.g because of their role in bacterial survival or their ability to discriminate strains.We present an R package for the study of prokaryotic pan-genomes. The R computing environment harbors endless possibilities with respect to statistical analyses and graphics. External free software is used for the heavy computations involved, and the R package provides functions for building a computational pipeline.We demonstrate parts of the package on a data set for the gram positive bacterium Enterococcus faecalis. The package is free to download and install from The Comprehensive R Archive Network.


July 7, 2019

Comprehensive molecular, genomic and phenotypic analysis of a major clone of Enterococcus faecalis MLST ST40.

Enterococcus faecalis is a multifaceted microorganism known to act as a beneficial intestinal commensal bacterium. It is also a dreaded nosocomial pathogen causing life-threatening infections in hospitalised patients. Isolates of a distinct MLST type ST40 represent the most frequent strain type of this species, distributed worldwide and originating from various sources (animal, human, environmental) and different conditions (colonisation/infection). Since enterococci are known to be highly recombinogenic we determined to analyse the microevolution and niche adaptation of this highly distributed clonal type.We compared a set of 42 ST40 isolates by assessing key molecular determinants, performing whole genome sequencing (WGS) and a number of phenotypic assays including resistance profiling, formation of biofilm and utilisation of carbon sources. We generated the first circular closed reference genome of an E. faecalis isolate D32 of animal origin and compared it with the genomes of other reference strains. D32 was used as a template for detailed WGS comparisons of high-quality draft genomes of 14 ST40 isolates. Genomic and phylogenetic analyses suggest a high level of similarity regarding the core genome, also demonstrated by similar carbon utilisation patterns. Distribution of known and putative virulence-associated genes did not differentiate between ST40 strains from a commensal and clinical background or an animal or human source. Further analyses of mobile genetic elements (MGE) revealed genomic diversity owed to: (1) a modularly structured pathogenicity island; (2) a site-specifically integrated and previously unknown genomic island of 138 kb in two strains putatively involved in exopolysaccharide synthesis; and (3) isolate-specific plasmid and phage patterns. Moreover, we used different cell-biological and animal experiments to compare the isolate D32 with a closely related ST40 endocarditis isolate whose draft genome sequence was also generated. D32 generally showed a greater capacity of adherence to human cell lines and an increased pathogenic potential in various animal models in combination with an even faster growth in vivo (not in vitro).Molecular, genomic and phenotypic analysis of representative isolates of a major clone of E. faecalis MLST ST40 revealed new insights into the microbiology of a commensal bacterium which can turn into a conditional pathogen.


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