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July 7, 2019  |  

Complete genome sequences of historic Clostridioides difficile food-dwelling ribotype 078 strains in Canada identical to that of the historic human clinical strain M120 in the United Kingdom.

Clostridioides (Clostridium) difficile is a spore-forming anaerobic bacte- rium that causes severe intestinal diseases in humans. Here, we report the complete genome sequence of the first C. difficile foodborne type strain (PCR ribotype 078) isolated from food animals in Canada in 2004, which has 100% similarity to the ge- nome sequence of the historic human clinical strain M120.


July 7, 2019  |  

Complete genome sequence of Bacillus megaterium strain TG1-E1, a plant drought tolerance-enhancing bacterium.

Based on a combination of next-generation sequencing and single-molecule sequencing, we obtained the whole-genome sequence of Bacillus megaterium strain TG1-E1, which is a highly salt-tolerant rhizobacterium that enhances plant tolerance to drought stress. The complete genome is estimated to be approximately 5.48 Mb containing a total of 5,858 predicted protein-coding DNA sequences.


July 7, 2019  |  

Complete genome sequence of a wild-type isolate of Caulobacter vibrioides strain CB1.

The complete genome sequence of Caulobacter vibrioides strain CB1 consists of a chromosome of 4,137,285 bp, with a GC content of 67.2% and 3,990 coding DNA sequences. This strain contains the typical genome rearrangement that is characteristic of the Caulobacter strains that are currently sequenced. However, this strain is so closely related to sequenced strain NA1000 that rearrangements were minimal. This will allow further clarification of the causes of rearrangements in the species.


July 7, 2019  |  

Complete genome sequences of two Rhodobacter strains.

We report the complete genome sequences of two strains of the Alphaproteobacteria genus Rhodobacter, Rhodobacter blasticus 28/5, the source of the commercially available enzyme RsaI, and a new isolate of Rhodobacter sphaeroides 2.4.1. Both strains contain multiple restriction-modification systems, and their DNA methylation motifs are included in this report.


July 7, 2019  |  

New variant of multidrug-resistant Salmonella enterica serovar Typhimurium associated with invasive disease in immunocompromised patients in Vietnam.

Nontyphoidal Salmonella (NTS), particularly Salmonella enterica serovar Typhimurium, is among the leading etiologic agents of bacterial enterocolitis globally and a well-characterized cause of invasive disease (iNTS) in sub-Saharan Africa. In contrast, S Typhimurium is poorly defined in Southeast Asia, a known hot spot for zoonotic disease with a recently described burden of iNTS disease. Here, we aimed to add insight into the epidemiology and potential impact of zoonotic transfer and antimicrobial resistance (AMR) in S Typhimurium associated with iNTS and enterocolitis in Vietnam. We performed whole-genome sequencing and phylogenetic reconstruction on 85 human (enterocolitis, carriage, and iNTS) and 113 animal S Typhimurium isolates isolated in Vietnam. We found limited evidence for the zoonotic transmission of S Typhimurium. However, we describe a chain of events where a pandemic monophasic variant of S Typhimurium (serovar I:4,[5],12:i:- sequence type 34 [ST34]) has been introduced into Vietnam, reacquired a phase 2 flagellum, and acquired an IncHI2 multidrug-resistant plasmid. Notably, these novel biphasic ST34 S Typhimurium variants were significantly associated with iNTS in Vietnamese HIV-infected patients. Our study represents the first characterization of novel iNTS organisms isolated outside sub-Saharan Africa and outlines a new pathway for the emergence of alternative Salmonella variants into susceptible human populations.IMPORTANCESalmonella Typhimurium is a major diarrheal pathogen and associated with invasive nontyphoid Salmonella (iNTS) disease in vulnerable populations. We present the first characterization of iNTS organisms in Southeast Asia and describe a different evolutionary trajectory from that of organisms causing iNTS in sub-Saharan Africa. In Vietnam, the globally distributed monophasic variant of Salmonella Typhimurium, the serovar I:4,[5],12:i:- ST34 clone, has reacquired a phase 2 flagellum and gained a multidrug-resistant plasmid to become associated with iNTS disease in HIV-infected patients. We document distinct communities of S Typhimurium and I:4,[5],12:i:- in animals and humans in Vietnam, despite the greater mixing of these host populations here. These data highlight the importance of whole-genome sequencing surveillance in a One Health context in understanding the evolution and spread of resistant bacterial infections. Copyright © 2018 Mather et al.


July 7, 2019  |  

Myxobacteria: Unraveling the potential of a unique microbiome niche

Natural products obtained from microorganisms have been playing an imperative role in drug discovery for decades. Hence, rightfully, microorganisms are considered as the richest source of biochemical remedies. In this review, we represent an unexplored family of bacteria considered to be prolific producers of diverse metabolites. Myxobacteria are gram-negative bacteria which have been reported to produce large families of secondary metabolites with prominent antimicrobial, antifungal, and antitumor activities. Klaus Gerth, Norbert Bedorf, Herbert Irschik, and Hans Reichenbach observed the antifungal activity of Sorangium cellulosum against Mucor hiemalis. In 2006, Hans Reichenbach and his team obtained a novel macrolide cruentaren A from Byssovorax cruenta (myxobacteria). Cruentaren A showed inhibitory activity against yeast and filamentous fungi. It also showed selective inhibitory activity against mitochondrial F-type ATPase. Cruentaren A has been found to be cytotoxic against various human cancer cell lines. In 2007, Reichenbach and his colleagues named an antibiotic produced by Sorangium cellulosum strain Soce895 as thuggacin. This antibiotic acts on the respiration of some bacteria. Other antibiotics from myxobacteria, myxovirescin, and megovalicin show broad-spectrum bactericidal activity. The College of Food and Bioengineering, Henan University of Science and Technology, Luoyang, China, evaluated the antitumor property of epothilone, which has shown promise for breast cancer treatment. The study determined high potential and versatile antimicrobial and antitumor secondary metabolites of myxobacteria. In yet another study, Ratjadone A, that exhibited strong antiviral activity against HIV, was obtained from Sorangium cellulosum strain. This compound shows antiviral activity in vitro but has low selectivity. Further search on the derivatives of this compound might help in the future. This is rationale enough to pre-empt that every strain of myxobacteria might be endowed to produce secondary metabolites with novel mechanisms of action which are rarely produced by other microbes. The available data establishes the impact of myxobacterial studies in search for novel metabolites as a front runner in microbiological research and worthy enough to be a thrust area of research in pharmacology.


July 7, 2019  |  

The molecular basis for the intramolecular migration (NIH shift) of the carboxyl group during para-hydroxybenzoate catabolism.

The NIH shift is a chemical rearrangement in which a substituent on an aromatic ring undergoes an intramolecular migration, primarily during an enzymatic hydroxylation reaction. The molecular mechanism for the NIH shift of a carboxyl group has remained a mystery for 40 years. Here, we elucidate the molecular mechanism of the reaction in the conversion of para-hydroxybenzoate (PHB) to gentisate (GA, 2, 5-dihydroxybenzoate). Three genes (phgABC) from the PHB utilizer Brevibacillus laterosporus PHB-7a encode enzymes (p-hydroxybenzoyl-CoA ligase, p-hydroxybenzoyl-CoA hydroxylase and gentisyl-CoA thioesterase, respectively) catalyzing the conversion of PHB to GA via a route involving CoA thioester formation, hydroxylation concomitant with a 1, 2-shift of the acetyl CoA moiety and thioester hydrolysis. The shift of the carboxyl group was established rigorously by stable isotopic experiments with heterologously expressed phgABC, converting 2, 3, 5, 6-tetradeutero-PHB and [carboxyl-13 C]-PHB to 3, 4, 6-trideutero-GA and [carboxyl-13 C]-GA respectively. This is distinct from the NIH shifts of hydrogen and aceto substituents, where a single oxygenase catalyzes the reaction without the involvement of a thioester. The discovery of this three-step strategy for carboxyl group migration reveals a novel role of the CoA thioester in biochemistry and also illustrates the diversity and complexity of microbial catabolism in the carbon cycle.© 2018 John Wiley & Sons Ltd.


July 7, 2019  |  

Genomic features of the Helicobacter pylori strain PMSS1 and its virulence attributes as deduced from its in vivo colonisation patterns.

The human gastric pathogen Helicobacter pylori occurs in two basic variants, either exhibiting a functional cagPAI-encoded type-4-secretion-system (T4SS) or not. Only a few cagPAI-positive strains have been successfully adapted for long-term infection of mice, including the pre-mouse Sydney strain 1 (PMSS1). Here we confirm that PMSS1 induces gastric inflammation and neutrophil infiltration in mice, progressing to intestinal metaplasia. Complete genome analysis of PMSS1 revealed 1,423 coding sequences, encompassing the cagPAI gene cluster and, unusually, the location of the cytotoxin-associated gene A (cagA) approximately 15 kb downstream of the island. PMSS1 harbours three genetically exchangeable loci that are occupied by the hopQ coding sequences. HopQ represents a critical co-factor required for the translocation of CagA into the host cell and activation of NF-?B via the T4SS. Long-term colonisation of mice led to an impairment of cagPAI functionality. One of the bacterial clones re-isolated at four months post-infection revealed a mutation in the cagPAI gene cagW, resulting in a frame shift mutation, which prevented CagA translocation, possibly due to an impairment of T4SS function. Rescue of the mutant cagW re-established CagA translocation. Our data reveal intriguing insights into the adaptive abilities of PMSS1, suggesting functional modulation of the H. pylori cagPAI virulence attribute.© 2018 The Authors. Molecular Microbiology Published by John Wiley & Sons Ltd.


July 7, 2019  |  

Measuring the mappability spectrum of reference genome assemblies

The ability to infer actionable information from genomic variation data in a resequencing experiment relies on accurately aligning the sequences to a reference genome. However, this accuracy is inherently limited by the quality of the reference assembly and the repetitive content of the subject’s genome. As long read sequencing technologies become more widespread, it is crucial to investigate the expected improvements in alignment accuracy and variant analysis over existing short read methods. The ability to quantify the read length and error rate necessary to uniquely map regions of interest in a sequence allows users to make informed decisions regarding experiment design and provides useful metrics for comparing the magnitude of repetition across different reference assemblies. To this end we have developed NEAT-Repeat, a toolkit for exhaustively identifying the minimum read length required to uniquely map each position of a reference sequence given a specified error rate. Using these tools we computed the -mappability spectrum” for ten reference sequences, including human and a range of plants and animals, quantifying the theoretical improvements in alignment accuracy that would result from sequencing with longer reads or reads with less base-calling errors. Our inclusion of read length and error rate builds upon existing methods for mappability tracks based on uniqueness or aligner-specific mapping scores, and thus enables more comprehensive analysis. We apply our mappability results to whole-genome variant call data, and demonstrate that variants called with low mapping and genotype quality scores are disproportionately found in reference regions that require long reads to be uniquely covered. We propose that our mappability metrics provide a valuable supplement to established variant filtering and annotation pipelines by supplying users with an additional metric related to read mapping quality. NEAT-Repeat can process large and repetitive genomes, such as those of corn and soybean, in a tractable amount of time by leveraging efficient methods for edit distance computation as well as running multiple jobs in parallel. NEAT-Repeat is written in Python 2.7 and C++, and is available at https://github.com/zstephens/neat-repeat.


July 7, 2019  |  

The complete genomic sequence of a novel cold-adapted bacterium, Planococcus maritimus Y42, isolated from crude oil-contaminated soil.

Planococcus maritimus Y42, isolated from the petroleum-contaminated soil of the Qaidam Basin, can use crude oil as its sole source of carbon and energy at 20 °C. The genome of P. maritimus strain Y42 has been sequenced to provide information on its properties. Genomic analysis shows that the genome of strain Y42 contains one circular DNA chromosome with a size of 3,718,896 bp and a GC content of 48.8%, and three plasmids (329,482; 89,073; and 12,282 bp). Although the strain Y42 did not show a remarkably higher ability in degrading crude oil than other oil-degrading bacteria, the existence of strain Y42 played a significant role to reducing the overall environmental impact as an indigenous oil-degrading bacterium. In addition, genome annotation revealed that strain Y42 has many genes responsible for hydrocarbon degradation. Structural features of the genomes might provide a competitive edge for P. maritimus strain Y42 to survive in oil-polluted environments and be worthy of further study in oil degradation for the recovery of crude oil-polluted environments.


July 7, 2019  |  

One complete and three draft genome sequences of four Brochothrix thermosphacta strains, CD 337, TAP 175, BSAS1 3 and EBP 3070.

Brochothrix thermosphacta is one of the dominant bacterial species associated with spoilage of chilled meat and seafood products through the production of various metabolites responsible for off-odors. However, metabolic pathways leading to meat and seafood spoilage are not all well known. The production of spoiling molecules seems to depend both on strains and on food matrix. Several B. thermosphacta genome sequences have been reported, all issued from meat isolates. Here, we report four genome sequences, one complete and three as drafts. The four B. thermosphacta strains CD 337, TAP 175, BSAS1 3, and EBP 3070 were isolated from different ecological niches (seafood or meat products either spoiled or not and bovine slaughterhouse). These strains known as phenotypically and genetically different were selected to represent intraspecies diversity. CD 337 genome is 2,594,337 bp long, complete and circular, containing 2593 protein coding sequences and 28 RNA genes. TAP 175, BSAS1 3, and EBP 3070 genomes are arranged in 57, 83, and 71 contigs, containing 2515, 2668, and 2611 protein-coding sequences, respectively. These genomes were compared with two other B. thermosphacta complete genome sequences. The main genome content differences between strains are phages, plasmids, restriction/modification systems, and cell surface functions, suggesting a similar metabolic potential but a different niche adaptation capacity.


July 7, 2019  |  

PacBio genome sequences of Escherichia coli serotype O157:H7, diffusely adherent E. coli, and Salmonella enterica strains, all carrying plasmids with an mcr-1 resistance gene.

We report here Illumina-corrected PacBio whole-genome sequences of an Escherichia coli serotype O157:H7 strain (2017C-4109), an E. coli serotype O[undetermined]:H2 strain (2017C-4173W12), and a Salmonella enterica subsp. enterica serovar Enteritidis strain (2017K-0021), all of which carried the mcr-1 resistance gene on an IncI2 or IncX4 plasmid. We also determined that pMCR-1-CTSe is identical to a previously published plasmid, pMCR-1-CT.


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