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July 7, 2019

Identification of Pseudomonas mosselii BS011 gene clusters required for suppression of Rice Blast Fungus Magnaporthe oryzae.

Pseudomonas is a Gram-negative, rod-shaped bacteria. Many members of this genus displayed remarkable physiological and metabolic activity against different plant pathogens. However, Pseudomonas mosselii has not yet been characterized in biocontrol against plant disease. Here we isolated a strain of P. mosselii BS011 from the rhizosphere soil of rice plants, and the isolate showed strong inhibitory activity against the rice blast fungus Magnaporthe oryzae. Further we sequenced the complete genome of BS011, which consist of 5.75?Mb with a circular chromosome, 5,170 protein-coding genes, 23 rRNA and 78 tRNA operons. Bioinformatic analysis revealed that seven gene clusters may be involved in the biosynthesis of metabolites. Gene deletion experiments demonstrated that the gene cluster c-xtl is required for inhibitory activity against M. oryzae. Bioassay showed that the crude extract from BS011 fermentation sample significantly inhibited the development of M. oryzae at a concentration of 10?µg/ml. Besides, we illustrated that the crude extract of BS011 impaired the appressorial formation in a dose dependent manner. Collectively our results revealed that P. mosselii BS011 is a promising biocontrol agent and the gene cluster c-xtl is essential for inhibiting the development of M. oryzae. Copyright © 2018. Published by Elsevier B.V.

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July 7, 2019

Phylogeny of dermatophytes with genomic character evaluation of clinically distinct Trichophyton rubrum and T. áviolaceum

Trichophyton rubrum and T. violaceum are prevalent agents of human dermatophyte infections, the former being found on glabrous skin and nail, while the latter is confined to the scalp. The two species are phenotypically different but are highly similar phylogenetically. The taxonomy of dermatophytes is currently being reconsidered on the basis of molecular phylogeny. Molecular species definitions do not always coincide with existing concepts which are guided by ecological and clinical principles. In this article, we aim to bring phylogenetic and ecological data together in an attempt to develop new species concepts for anthropophilic dermatophytes. Focus is on the T. rubrum complex with analysis of rDNA ITS supplemented with LSU, TUB2, TEF3 and ribosomal protein L10 gene sequences. In order to explore genomic differences between T. rubrum and T. violaceum, one representative for both species was whole genome sequenced. Draft sequences were compared with currently available dermatophyte genomes. Potential virulence factors of adhesins and secreted proteases were predicted and compared phylogenetically. General phylogeny showed clear gaps between geophilic species of Arthroderma, but multilocus distances between species were often very small in the derived anthropophilic and zoophilic genus Trichophyton. Significant genome conservation between T. rubrum and T. violaceum was observed, with a high similarity at the nucleic acid level of 99.38 % identity. Trichophyton violaceum contains more paralogs than T. rubrum. About 30 adhesion genes were predicted among dermatophytes. Seventeen adhesins were common between T. rubrum and T. violaceum, while four were specific for the former and eight for the latter. Phylogenetic analysis of secreted proteases reveals considerable expansion and conservation among the analyzed species. Multilocus phylogeny and genome comparison of T. rubrum and T. violaceum underlined their close affinity. The possibility that they represent a single species exhibiting different phenotypes due to different localizations on the human body is discussed.

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July 7, 2019

The case for not masking away repetitive DNA

In the course of analyzing whole-genome data, it is common practice to mask or filter out repetitive regions of a genome, such as transposable elements and endogenous retroviruses, in order to focus only on genes and thus simplify the results. This Commentary is a plea from one member of the Mobile DNA community to all gene-centric researchers: please do not ignore the repetitive fraction of the genome. Please stop narrowing your findings by only analyzing a minority of the genome, and instead broaden your analyses to include the rich biology of repetitive and mobile DNA. In this article, I present four arguments supporting a case for retaining repetitive DNA in your genome-wide analysis.

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July 7, 2019

Complete genome sequence of Gordonia sp. YC-JH1, a bacterium efficiently degrading a wide range of phthalic acid esters.

Phthalic acid esters (PAEs) are a family of recalcitrant pollutants mainly used as plasticizer. The strain Gordonia sp.YC-JH1, isolated from petroleum-contaminated soil, is capable of efficiently degrading a wide range of PAEs. In order to pertinently investigate the genetic mechanism of PAEs catabolism by strain YC-JH1, its complete genome sequencing has been performed by SMRT sequencing technology. The genome comprises a circular chromosome and a plasmid with a size of 4,101,557 bp and 91,767 bp respectively. Based on the genome sequence, 3563 protein-coding genes are predicted, of which the genes responsible for PAEs degradation are identified, including the two genes of PAEs hydrolase and the gene clusters for phthalic acid and protocatechuic acid degradation. The genome information provides genomic basis of PAEs degradation to allow the complete metabolism of PAEs. The wide substrate spectrum and its genetic basis of this strain should expand its application potential for environments bioremediation, provide novel gene resources involved in PAEs degradation for biotechnology and gene engineering, and contribute to shed light on the mechanism of PAEs metabolism. Copyright © 2018. Published by Elsevier B.V.

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July 7, 2019

Probiotic genomes: Sequencing and annotation in the past decade

Probiotics are live microorganisms that confer many health benefits to the host when administered in adequate quantities. These health benefits have garnered much attention towards Probiotics and have given an impetus to their use as dietary supplements for the improvement of general health and as adjuvant therapies for certain diseases. The increased demand for probiotic products in the recent times has provided the thrust for probiotic research applied to several areas of human biology. The advances in genomic technologies have further facilitated the sequencing of the genomes of such probiotic bacteria and their genomic analyses to identify the genes that endow the beneficial effects they are known to exert. This work reviews the application of genomic strategies on probiotic bacteria, while providing the details about the probiotic strains whose genome sequences are available. It also consolidates the Genomic tools used for the sequencing, assembly and annotation of the probiotic genes and how it has helped in comparative genomic analyses.

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July 7, 2019

Complete genome sequence of Bacillus licheniformis BL-010.

The biodegradation of Aflatoxin B1 (AFB1) is an industry of increasing importance. Bacillus licheniformis BL-010 was isolated from the aflatoxin contaminated corn feed storage, and was shown to degrade AFB1 efficiently. Here we present the complete genome sequence of BL-010, the genome comprises 4,287,714 bp in a circular chromosome with a GC content of 46.12% and contains genes encoding AFB1 degrading enzymes. The genome sequence displayed that this strain contains genes involved in production of laccase, aromatic ring-opening dioxygenase which could detoxify AFB1. Complete genome sequence of the strain BL-010 can further provide the genomic basis for the biotechnological application of strain BL-010 as an effective way to degrade AFB1. Copyright © 2018 Elsevier Ltd. All rights reserved.

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July 7, 2019

Emerging mechanisms of antimicrobial resistance in bacteria and fungi: advances in the era of genomics.

Bacteria and fungi continue to develop new ways to adapt and survive the lethal or biostatic effects of antimicrobials through myriad mechanisms. Novel antibiotic resistance genes such as lsa(C), erm(44), VCC-1, mcr-1, mcr-2, mcr-3, mcr-4, bla KLUC-3 and bla KLUC-4 were discovered through comparative genomics and further functional studies. As well, mutations in genes that hitherto were unknown to confer resistance to antimicrobials, such as trm, PP2C, rpsJ, HSC82, FKS2 and Rv2887, were shown by genomics and transcomplementation assays to mediate antimicrobial resistance in Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecium, Saccharomyces cerevisae, Candida glabrata and Mycobacterium tuberculosis, respectively. Thus, genomics, transcriptomics and metagenomics, coupled with functional studies are the future of antimicrobial resistance research and novel drug discovery or design.

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July 7, 2019

Complete genome sequence of Celeribacter baekdonensis strain LH4, a thiosulfate-oxidizing alphaproteobacterial isolate from Gulf of Mexico continental slope sediments.

We report here the closed genome sequences of Celeribacter baekdonensis strain LH4 and five unnamed plasmids obtained through PacBio sequencing with 99.99% consensus concordance. The genomes contained several distinctive features not found in other published Celeribacter genomes, including the potential to aerobically degrade styrene and other phenolic compounds. Copyright © 2018 Flood et al.

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July 7, 2019

Optimise wheat A-genome.

The wild einkorn wheat Triticum urartu (Tu) is the A-genome progenitor of tetraploid (AABB) and hexaploid (AABBDD) wheat. A draft genome of Tu was published in 2013, but a better reference sequence is urgently needed by scientists and breeders. Hong-Qing Ling, from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and colleagues have now completed a high-quality Tu genome using multiple methods.

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July 7, 2019

RIFRAF: a frame-resolving consensus algorithm.

Protein coding genes can be studied using long-read next generation sequencing. However, high rates of indel sequencing errors are problematic, corrupting the reading frame. Even the consensus of multiple independent sequence reads retains indel errors. To solve this problem, we introduce Reference-Informed Frame-Resolving multiple-Alignment Free template inference algorithm (RIFRAF), a sequence consensus algorithm that takes a set of error-prone reads and a reference sequence and infers an accurate in-frame consensus. RIFRAF uses a novel structure, analogous to a two-layer hidden Markov model: the consensus is optimized to maximize alignment scores with both the set of noisy reads and with a reference. The template-to-reads component of the model encodes the preponderance of indels, and is sensitive to the per-base quality scores, giving greater weight to more accurate bases. The reference-to-template component of the model penalizes frame-destroying indels. A local search algorithm proceeds in stages to find the best consensus sequence for both objectives.Using Pacific Biosciences SMRT sequences from an HIV-1 env clone, NL4-3, we compare our approach to other consensus and frame correction methods. RIFRAF consistently finds a consensus sequence that is more accurate and in-frame, especially with small numbers of reads. It was able to perfectly reconstruct over 80% of consensus sequences from as few as three reads, whereas the best alternative required twice as many. RIFRAF is able to achieve these results and keep the consensus in-frame even with a distantly related reference sequence. Moreover, unlike other frame correction methods, RIFRAF can detect and keep true indels while removing erroneous ones.RIFRAF is implemented in Julia, and source code is publicly available at https://github.com/MurrellGroup/Rifraf.jl.Supplementary data are available at Bioinformatics online.

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July 7, 2019

Auroramycin, a potent antibiotic from Streptomyces roseosporus by CRISPR-Cas9 activation.

Silent biosynthetic gene clusters represent a potentially rich source for new bioactive compounds. We report the discovery, characterization and biosynthesis of a novel doubly glycosylated 24-membered polyene macrolactam from a silent biosynthetic gene cluster in Streptomyces roseosporus using the CRISPR-Cas9 gene cluster activation strategy. Structural characterization of this polyketide, named auroramycin, revealed a rare isobutyrylmalonyl extender unit and a unique pair of aminosugars. Relative and absolute stereochemistry were determined using a combination of spectroscopic analyses, chemical derivatization, and computational analysis. The activated gene cluster for auroramycin production was also verified by transcriptional analyses and gene deletions. Finally, auroramycin exhibited potent anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activity towards clinical drug-resistant isolates.© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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July 7, 2019

Complete genome sequences of three Bacillus amyloliquefaciens strains that inhibit the growth of Listeria monocytogenes in vitro.

Here, we report the complete genome sequences of three Bacillus amyloliquefaciens strains isolated from alfalfa, almond drupes, and grapes that inhibited the growth of Listeria monocytogenes strain 2011L-2857 in vitro We also report multiple gene clusters encoding secondary metabolites that may be responsible for the growth inhibition of L. monocytogenes. Copyright © 2018 Tran et al.

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July 7, 2019

The challenge of analyzing the sugarcane genome.

Reference genome sequences have become key platforms for genetics and breeding of the major crop species. Sugarcane is probably the largest crop produced in the world (in weight of crop harvested) but lacks a reference genome sequence. Sugarcane has one of the most complex genomes in crop plants due to the extreme level of polyploidy. The genome of modern sugarcane hybrids includes sub-genomes from two progenitors Saccharum officinarum and S. spontaneum with some chromosomes resulting from recombination between these sub-genomes. Advancing DNA sequencing technologies and strategies for genome assembly are making the sugarcane genome more tractable. Advances in long read sequencing have allowed the generation of a more complete set of sugarcane gene transcripts. This is supporting transcript profiling in genetic research. The progenitor genomes are being sequenced. A monoploid coverage of the hybrid genome has been obtained by sequencing BAC clones that cover the gene space of the closely related sorghum genome. The complete polyploid genome is now being sequenced and assembled. The emerging genome will allow comparison of related genomes and increase understanding of the functioning of this polyploidy system. Sugarcane breeding for traditional sugar and new energy and biomaterial uses will be enhanced by the availability of these genomic resources.

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July 7, 2019

Analysis of resistance genes of clinical Pannonibacter phragmitetus strain 31801 by complete genome sequencing.

To clarify the resistance mechanisms of Pannonibacter phragmitetus 31801, isolated from the blood of a liver abscess patient, at the genomic level, we performed whole genomic sequencing using a PacBio RS II single-molecule real-time long-read sequencer. Bioinformatic analysis of the resulting sequence was then carried out to identify any possible resistance genes. Analyses included Basic Local Alignment Search Tool searches against the Antibiotic Resistance Genes Database, ResFinder analysis of the genome sequence, and Resistance Gene Identifier analysis within the Comprehensive Antibiotic Resistance Database. Prophages, clustered regularly interspaced short palindromic repeats (CRISPR), and other putative virulence factors were also identified using PHAST, CRISPRfinder, and the Virulence Factors Database, respectively. The circular chromosome and single plasmid of P. phragmitetus 31801 contained multiple antibiotic resistance genes, including those coding for three different types of ß-lactamase [NPS ß-lactamase (EC 3.5.2.6), ß-lactamase class C, and a metal-dependent hydrolase of ß-lactamase superfamily I]. In addition, genes coding for subunits of several multidrug-resistance efflux pumps were identified, including those targeting macrolides (adeJ, cmeB), tetracycline (acrB, adeAB), fluoroquinolones (acrF, ceoB), and aminoglycosides (acrD, amrB, ceoB, mexY, smeB). However, apart from the tripartite macrolide efflux pump macAB-tolC, the genome did not appear to contain the complete complement of subunit genes required for production of most of the major multidrug-resistance efflux pumps.

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