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July 7, 2019

Comparative analysis of an IncR plasmid carrying armA, blaDHA-1 and qnrB4 from Klebsiella pneumoniae ST37 isolates.

The objective of this study was to conduct a comparative analysis with reported IncR plasmids of a Klebsiella pneumoniae IncR plasmid carrying an MDR region.MDR K. pneumoniae isolates were serially identified from two inpatients at a hospital in the USA in 2014. MDR plasmid pYDC676 was fully sequenced, annotated and compared with related plasmids. Antimicrobial susceptibility testing, PFGE and MLST were also conducted.The K. pneumoniae isolates were identical by PFGE, belonged to ST37 and harboured an identical ~50 kb IncR plasmid (pYDC676). pYDC676 possessed the backbone and multi-IS loci closely related to IncR plasmids reported from aquatic bacteria, as well as animal and human K. pneumoniae strains, and carried an MDR region consisting of armA, blaDHA-1 and qnrB4, a combination that has been reported in IncR plasmids from K. pneumoniae ST11 strains in Europe and Asia. A plasmid with the identical IncR backbone and a similar MDR region containing blaDHA-1 and qnrB4 has also been reported in ST37 strains from Europe, suggesting potential dissemination of this lineage of IncR plasmids in K. pneumoniae ST37.K. pneumoniae ST37 strains with an MDR IncR plasmid carrying armA, blaDHA-1 and qnrB4 were identified in a hospital in the USA, where these resistance genes remain rare. The IncR backbone may play a role in the global dissemination of these resistance genes.© The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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July 7, 2019

Genome of Cnaphalocrocis medinalis granulovirus, the first Crambidae-infecting betabaculovirus isolated from rice leaffolder to sequenced.

Cnaphalocrocis medinalis is a major pest of rice in South and South-East Asia. Insecticides are the major means farmers use for management. A naturally occurring baculovirus, C. medinalis granulovirus (CnmeGV), has been isolated from the larvae and this has the potential for use as microbial agent. Here, we described the complete genome sequence of CnmeGV and compared it to other baculovirus genomes. The genome of CnmeGV is 112,060 base pairs in length, has a G+C content of 35.2%. It contains 133 putative open reading frames (ORFs) of at least 150 nucleotides. A hundred and one (101) of these ORFs are homologous to other baculovirus genes including 37 baculovirus core genes. Thirty-two (32) ORFs are unique to CnmeGV with no homologues detected in the GeneBank and 53 tandem repeats (TRs) with sequence length from 25 to 551 nt intersperse throughout the genome of CnmeGV. Six (6) homologous regions (hrs) were identified interspersed throughout the genome. Hr2 contains 11 imperfect palindromes and a high content of AT sequence (about 73%). The unique ORF28 contains a coiled-coil region and a zinc finger-like domain of 4-50 residues specialized by two C2C2 zinc finger motifs that putatively bound two atoms of zinc. ORF21 encoding a chit-1 protein suggesting a horizontal gene transfer from alphabaculovirus. The putative protein presents two carbohydrate-binding module family 14 (CBM_14) domains rather than other homologues detected from betabaculovirus that only contains one chit-binding region. Gene synteny maps showed the colinearity of sequenced betabaculovirus. Phylogenetic analysis indicated that CnmeGV grouped in the betabaculovirus, with a close relation to AdorGV. The cladogram obtained in this work grouped the 17 complete GV genomes in one monophyletic clade. CnmeGV represents a new crambidae host-isolated virus species from the genus Betabaculovirus and is most closely relative of AdorGV. The analyses and information derived from this study will provide a better understanding of the pathological symptoms caused by this virus and its potential use as a microbial pesticide.

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July 7, 2019

Multiple mechanisms responsible for strong Congo-red-binding variants of Escherichia coli O157:H7 strains.

High variability in the expression of csgD-dependent, biofilm-forming and adhesive properties is common among Shiga toxin-producing Escherichia coli. Although many strains of serotype O157:H7 form little biofilm, conversion to stronger biofilm phenotypes has been observed. In this study, we screened different strains of serotype O157:H7 for the emergence of strong Congo-red (CR) affinity/biofilm-forming properties and investigated the underlying genetic mechanisms. Two major mechanisms which conferred stronger biofilm phenotypes were identified: mutations (insertion, deletion, single nucleotide change) in rcsB region and stx-prophage excision from the mlrA site. Restoration of the native mlrA gene (due to prophage excision) resulted in strong biofilm properties to all variants. Whereas RcsB mutants showed weaker CR affinity and biofilm properties, it provided more possibilities for phenotypic presentations through heterogenic sequence mutations. Published by Oxford University Press on behalf of FEMS 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

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July 7, 2019

A phylogenetic and phenotypic analysis of Salmonella enterica serovar Weltevreden, an emerging agent of diarrheal disease in tropical regions.

Salmonella enterica serovar Weltevreden (S. Weltevreden) is an emerging cause of diarrheal and invasive disease in humans residing in tropical regions. Despite the regional and international emergence of this Salmonella serovar, relatively little is known about its genetic diversity, genomics or virulence potential in model systems. Here we used whole genome sequencing and bioinformatics analyses to define the phylogenetic structure of a diverse global selection of S. Weltevreden. Phylogenetic analysis of more than 100 isolates demonstrated that the population of S. Weltevreden can be segregated into two main phylogenetic clusters, one associated predominantly with continental Southeast Asia and the other more internationally dispersed. Subcluster analysis suggested the local evolution of S. Weltevreden within specific geographical regions. Four of the isolates were sequenced using long read sequencing to produce high quality reference genomes. Phenotypic analysis in Hep-2 cells and in a murine infection model indicated that S. Weltevreden were significantly attenuated in these models compared to the classical S. Typhimurium reference strain SL1344. Our work outlines novel insights into this important emerging pathogen and provides a baseline understanding for future research studies.

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July 7, 2019

Complete genome of Streptomyces hygroscopicus subsp. limoneus KCTC 1717 (=KCCM 11405), a soil bacterium producing validamycin and diverse secondary metabolites.

Streptomyces hygroscopicus subsp. limoneus is a Gram-positive, aerobic, aerial mycelial, spore-forming bacterium that was first isolated from a soil sample in Akashi City, Hyogo Prefecture, Japan. We here report the complete genome of S. hygroscopicus subsp. limoneus KCTC 1717 (=KCCM 11405=IFO 12704=ATCC 21432), which consists of 10,537,932bp (G+C content of 71.96%) with two linear chromosomes, 8983 protein-coding genes, 67 tRNAs and 6 rRNA operons. Genes related to biosynthesis of validamycin, valienamine and diverse secondary metabolites were detected in this genome. Genomic data is thus expected to considerably improve our understanding of how industrially important aminocyclitols are biosynthesized by microbial cells. Copyright © 2015 Elsevier B.V. All rights reserved.

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July 7, 2019

Complete genome sequence of the African strain AXO1947 of Xanthomonas oryzae pv. oryzae.

Xanthomonas oryzae pv. oryzae is the etiological agent of bacterial rice blight. Three distinct clades of X. oryzae pv. oryzae are known. We present the complete annotated genome of the African clade strain AXO194 using long-read single-molecule PacBio sequencing technology. The genome comprises a single chromosome of 4,674,975 bp and encodes for nine transcriptional activator-like (TAL) effectors. The approach and data presented in this announcement provide information for complex bacterial genome organization and the discovery of new virulence effectors, and they facilitate target characterization of TAL effectors. Copyright © 2016 Huguet-Tapia et al.

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July 7, 2019

Coevolution between Nuclear-encoded DNA replication, recombination, and repair genes and plastid genome complexity.

Disruption of DNA replication, recombination, and repair (DNA-RRR) systems has been hypothesized to cause highly elevated nucleotide substitution rates and genome rearrangements in the plastids of angiosperms, but this theory remains untested. To investigate nuclear-plastid genome (plastome) coevolution in Geraniaceae, four different measures of plastome complexity (rearrangements, repeats, nucleotide insertions/deletions, and substitution rates) were evaluated along with substitution rates of 12 nuclear-encoded, plastid-targeted DNA-RRR genes from 27 Geraniales species. Significant correlations were detected for nonsynonymous (dN) but not synonymous (dS) substitution rates for three DNA-RRR genes (uvrB/C, why1, and gyrA) supporting a role for these genes in accelerated plastid genome evolution in Geraniaceae. Furthermore, correlation between dN of uvrB/C and plastome complexity suggests the presence of nucleotide excision repair system in plastids. Significant correlations were also detected between plastome complexity and 13 of the 90 nuclear-encoded organelle-targeted genes investigated. Comparisons revealed significant acceleration of dN in plastid-targeted genes of Geraniales relative to Brassicales suggesting this correlation may be an artifact of elevated rates in this gene set in Geraniaceae. Correlation between dN of plastid-targeted DNA-RRR genes and plastome complexity supports the hypothesis that the aberrant patterns in angiosperm plastome evolution could be caused by dysfunction in DNA-RRR systems.© The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

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July 7, 2019

Draft genome sequences of the turfgrass pathogen Sclerotinia homoeocarpa.

Sclerotinia homoeocarpa (F. T. Bennett) is one of the most economically important pathogens on high-amenity cool-season turfgrasses, where it causes dollar spot. To understand the genetic mechanisms of fungicide resistance, which has become highly prevalent, the whole genomes of two isolates with varied resistance levels to fungicides were sequenced. Copyright © 2016 Green et al.

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July 7, 2019

Genomic analyses reveal that partial sequence of an earlier pseudorabies virus in China is originated from a Bartha-vaccine-like strain.

Pseudorabies virus (PRV), the causative agent of Aujeszky?s disease, has gained increased attention in China in recent years as a result of the outbreak of emergent pseudorabies. Several genomic and partial sequences are available for Chinese emergent and European-American strains of PRV, but limited sequence data exist for the earlier Chinese strains. In this study, we determined the complete genomic sequence of one earlier Chinese strain SC and one emergent strain HLJ8. Compared with other known sequences, we demonstrated that PRV strains from distinct geographical regions displayed divergent evolution. Additionally, we report for the first time, a recombination event between PRV strains, and show that strain SC is a recombinant of an endemic Chinese strain and a Bartha-vaccine-like strain. These results contribute to our understanding of PRV evolution. Copyright © 2016 Elsevier Inc. All rights reserved.

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July 7, 2019

Complete genome of Pseudomonas sp. strain L10.10, a psychrotolerant biofertilizer that could promote plant growth.

Pseudomonas sp. strain L10.10 (=DSM 101070) is a psychrotolerant bacterium which was isolated from Lagoon Island, Antarctica. Analysis of its complete genome sequence indicates its possible role as a plant-growth promoting bacterium, including nitrogen-fixing ability and indole acetic acid (IAA)-producing trait, with additional suggestion of plant disease prevention attributes via hydrogen cyanide production. Copyright © 2016 Elsevier B.V. All rights reserved.

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July 7, 2019

Large-scale mitogenomics enables insights into Schizophora (Diptera) radiation and population diversity.

True flies are insects of the order Diptera and encompass one of the most diverse groups of animals on Earth. Within dipterans, Schizophora represents a recent radiation of insects that was used as a model to develop a pipeline for generating complete mitogenomes using various sequencing platforms and strategies. 91 mitogenomes from 32 different species were sequenced and assembled with high fidelity, using amplicon, whole genome shotgun or single molecule sequencing approaches. Based on the novel mitogenomes, we estimate the origin of Schizophora within the Cretaceous-Paleogene (K-Pg) boundary, about 68.3?Ma. Detailed analyses of the blowfly family (Calliphoridae) place its origin at 22?Ma, concomitant with the radiation of grazing mammals. The emergence of ectoparasitism within calliphorids was dated 6.95?Ma for the screwworm fly and 2.3?Ma for the Australian sheep blowfly. Varying population histories were observed for the blowfly Chrysomya megacephala and the housefly Musca domestica samples in our dataset. Whereas blowflies (n?=?50) appear to have undergone selective sweeps and/or severe bottlenecks in the New World, houseflies (n?=?14) display variation among populations from different zoogeographical zones and low levels of gene flow. The reported high-throughput mitogenomics approach for insects enables new insights into schizophoran diversity and population history of flies.

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July 7, 2019

Genome analysis of three Pneumocystis species reveals adaptation mechanisms to life exclusively in mammalian hosts.

Pneumocystis jirovecii is a major cause of life-threatening pneumonia in immunosuppressed patients including transplant recipients and those with HIV/AIDS, yet surprisingly little is known about the biology of this fungal pathogen. Here we report near complete genome assemblies for three Pneumocystis species that infect humans, rats and mice. Pneumocystis genomes are highly compact relative to other fungi, with substantial reductions of ribosomal RNA genes, transporters, transcription factors and many metabolic pathways, but contain expansions of surface proteins, especially a unique and complex surface glycoprotein superfamily, as well as proteases and RNA processing proteins. Unexpectedly, the key fungal cell wall components chitin and outer chain N-mannans are absent, based on genome content and experimental validation. Our findings suggest that Pneumocystis has developed unique mechanisms of adaptation to life exclusively in mammalian hosts, including dependence on the lungs for gas and nutrients and highly efficient strategies to escape both host innate and acquired immune defenses.

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