Drug-resistant Shigella sonnei poses a clinical and public health challenge. We report here the high-quality draft whole-genome sequences of four outbreak-associated S. sonnei isolates; three were resistant to two or more antibiotics, and one was resistant to streptomycin only.
Natural killer (NK) cells are a diverse population of lymphocytes with a range of biological roles including essential immune functions. NK cell diversity is in part created by the differential expression of cell surface receptors which modulate activation and function, including multiple subfamilies of C-type lectin receptors encoded within the NK complex (NKC). Little is known about the gene content of the NKC beyond rodent and primate lineages, other than it appears to be extremely variable between mammalian groups. We compared the NKC structure between mammalian species using new high-quality draft genome assemblies for cattle and goat; re-annotated sheep, pig, and horse genome assemblies; and the published human, rat, and mouse lemur NKC. The major NKC genes are largely in the equivalent positions in all eight species, with significant independent expansions and deletions between species, allowing us to propose a model for NKC evolution during mammalian radiation. The ruminant species, cattle and goats, have independently evolved a second KLRC locus flanked by KLRA and KLRJ, and a novel KLRH-like gene has acquired an activating tail. This novel gene has duplicated several times within cattle, while other activating receptor genes have been selectively disrupted. Targeted genome enrichment in cattle identified varying levels of allelic polymorphism between the NKC genes concentrated in the predicted extracellular ligand-binding domains. This novel recombination and allelic polymorphism is consistent with NKC evolution under balancing selection, suggesting that this diversity influences individual immune responses and may impact on differential outcomes of pathogen infection and vaccination.
To analyse and compare mcr-1-bearing plasmids from animal Escherichia coli isolates, and to investigate potential mechanisms underlying dissemination of mcr-1.Ninety-seven ESBL-producing E. coli strains isolated from pig farms in China were screened for the mcr-1 gene. Fifteen mcr-1-positive strains were subjected to molecular characterization and bioinformatic analysis of the mcr-1-bearing plasmids that they harboured.Three major types of mcr-1-bearing plasmids were recovered: IncX4 (~33 kb), IncI2 (~60 kb) and IncHI2 (~216-280 kb), among which the IncX4 and IncI2 plasmids were found to harbour the mcr-1 gene only, whereas multiple resistance elements including blaCTX-M, blaCMY, blaTEM, fosA, qnrS, floR and oqxAB were detected, in various combinations, alongside mcr-1 in the IncHI2 plasmids. The profiles of mcr-1-bearing plasmids in the test strains were highly variable, with coexistence of two mcr-1-bearing plasmids being common. However, the MIC of colistin was not affected by the number of mcr-1-carrying plasmids harboured. Comparative analysis of the plasmids showed that they contained an mcr-1 gene cassette with varied structures (mcr-1-orf, ISApl1-mcr-1-orf and Tn6330), with the IncHI2 type being the most active in acquiring foreign resistance genes. A novel transposon, Tn6330, with the structure ISApl1-mcr-1-orf-ISApl1 was found to be the key element mediating translocation of mcr-1 into various plasmid backbones through formation of a circular intermediate.The mcr-1 gene can be disseminated via multiple mobile elements including Tn6330, its circular intermediate and plasmids harbouring such elements. It is often co-transmitted with other resistance determinants through IncHI2 plasmids. The functional mechanism of Tn6330, a typical composite transposon harbouring mcr-1, should be further investigated.© 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.
Antagonistic soil microorganisms, which are non-toxic, harmless non-pollutants, can effectively reduce the density of pathogenic species by some ways. Bacillus velezensis strain S3-1 was isolated from the rhizosphere soil of cucumber, and was shown to inhibit plant pathogens, promote plant growth and efficiently colonize rhizosphere soils. The strain produced 13 kinds of lipopeptide antibiotics, belonging to the surfactin, iturin and fengycin families. Here, we presented the complete genome sequence of S3-1. The genome consists of one chromosome without plasmids and also contains the biosynthetic gene cluster that encodes difficidin, macrolactin, surfactin and fengycin. The genome contains 86 tRNA genes, 27 rRNA genes and 57 antibiotic-related genes. The complete genome sequence of B. velezensis S3-1 provides useful information to further detect the molecular mechanisms behind antifungal actions, and will facilitate its potential as a biological pesticide in the agricultural industry. Copyright © 2017 Elsevier B.V. All rights reserved.
Buprofezin is a widely used insect growth regulator whose residue has been frequently detected in the environment, posing a threat to aquatic organisms and non-target insects. Microorganisms play an important role in the degradation of buprofezin in the natural environment. However, the relevant catabolic pathway has not been fully characterized, and the molecular mechanism of catabolism is still completely unknown. Rhodococcus qingshengii YL-1 can utilize buprofezin as a sole source of carbon and energy for growth. In this study, the upstream catabolic pathway in strain YL-1 was identified using tandem mass spectrometry. Buprofezin is composed of a benzene ring and a heterocyclic ring. The degradation is initiated by the dihydroxylation of the benzene ring and continues via dehydrogenation, aromatic ring cleavage, breaking of an amide bond and the release of the heterocyclic ring 2-tert-butylimino-3-isopropyl-1,3,5-thiadiazinan-4-one (2-BI). A buprofezin degradation-deficient mutant strain YL-0 was isolated. Comparative genomic analysis combined with gene deletion and complementation experiments revealed that the gene cluster bfzBA3A4A1A2C is responsible for the upstream catabolic pathway of buprofezin. bfzA3A4A1A2 encodes a novel Rieske non-heme iron oxygenase (RHO) system that is responsible for the dihydroxylation of buprofezin at the benzene ring; bfzB is involved in dehydrogenation, and bfzC is in charge of benzene ring cleavage. Furthermore, the products of bfzBA3A4A1A2C can also catalyze dihydroxylation, dehydrogenation and aromatic ring cleavage of biphenyl, flavanone, flavone and bifenthrin. In addition, a transcriptional study revealed that bfzBA3A4A1A2C is organized in one transcriptional unit that is constitutively expressed in strain YL-1.Importance There is an increasing concern about the residue and environmental fate of buprofezin. Microbial metabolism is an important mechanism responsible for the buprofezin degradation in natural environment. However, the molecular mechanism and genetic determinants of microbial degradation of buprofezin has not been well identified. This work revealed that gene cluster bfzBA3A4A1A2C is responsible for the upstream catabolic pathway of buprofezin in R. qingshengii YL-1. The products of bfzBA3A4A1A2C could also degrade bifenthrin, a widely used pyrethroid insecticide. These findings enhance our understanding of the microbial degradation mechanism of buprofezin and benefit the application of strain YL-1 and bfzBA3A4A1A2C in the bioremediation of buprofezin contamination. Copyright © 2017 American Society for Microbiology.
The draft genome sequence of the halophilic bacterium Halobacillus mangrovi KTB 131, isolated from Topan salt of the Jeon-nam in Korea, was established. The genome comprises 4,151,649 bp, with a G + C content of 41.6%. The strain displays a high number of genes responsible for secondary metabolite biosynthesis, transport, and catabolism compared to other Halobacillus bacterial genus members. Numerous genes responsible for various transport systems, solute accumulation, and aromatic/sulfur decomposition were detected. The first genomic analysis encourages further research on comparative genomics and potential biotechnological applications. The whole draft genome sequence of Halobacillus mangrovi KTB 131 is now available (Bioproject PRJNA380285).
Leuconostoc garlicum KCCM 43211 isolated from traditional Korean fermented food is an intensive producer of exopolysaccharide (EPS). Here we report the first complete genome sequence of L. garlicum KCCM 43211. The genome sequence displayed that this strain contains genes involved in production of EPS possibly composed of glucose monomers. An uncharacterized EPS from the L. garlicum KCCM 43211 strains was also produced during fermentation in the sucrose medium. The MALDI-TOF results displayed the typical mass spectrometry pattern of dextran. This uncharacterized EPS may have use in commercial prebiotics, food additives, and medical purposes. The complete genome sequence of L. garlicum KCCM 43211 will provide valuable information for strain engineering based on the genetic information. Copyright © 2017 Elsevier B.V. All rights reserved.
To characterize a novel virulence-resistance plasmid pSE380T carried by a Salmonella enterica serotype Enteritidis clinical strain SE380.The plasmid pSE380T was conjugated to Escherichia coli strain J53 and sequenced by PacBio RSII, followed by subsequent annotation and genetic analysis.Sequence analysis of this plasmid revealed that the entire Salmonella Enteritidis-specific virulence plasmid, pSEN, had been incorporated into an IncHI2 MDR plasmid, which comprises the cephalosporin and fosfomycin resistance determinants blaCTX-M-14 and fosA3. Based on BLAST analysis and scrutiny of insertion footprints, the insertion event was found to involve a replicative transposition process mediated by IS26, an IS element frequently detected in various resistance plasmids. The resulting pSE380T plasmid also comprises backbone elements of IncHI2 and IncFIA plasmids, producing a rare fusion product that simultaneously encodes functional features of both, i.e. virulence, resistance and high transmissibility.This is a novel hybrid plasmid mediating MDR and virulence from a clinical Salmonella Enteritidis strain. This plasmid is likely to be transmissible amongst various serotypes of Salmonella and other Enterobacteriaceae species, rendering a wide range of bacterial pathogens resistant to cephalosporins and fosfomycin, and further enhancing their virulence potential. It will be important to monitor the spread and further evolution of this plasmid among the Enterobacteriaceae strains.© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Here we report the comparative genomic analysis of strain UJ101 with 15 strains from the family Flavobacteriaceae, using the CGExplorer program. Flavobacteriales bacterium strain UJ101 was isolated from a xanthid crab, Atergatis reticulatus, from the East Sea near Korea. The complete genome of strain UJ101 is a 3,074,209 bp, single, circular chromosome with 30.74% GC content. While the UJ101 genome contains a number of annotated genes for many metabolic pathways, such as the Embden-Meyerhof pathway, the pentose phosphate pathway, the tricarboxylic acid (TCA) cycle, and the glyoxylate cycle, genes for the Entner-Douddoroff pathway are not found in the UJ101 genome. Overall, carbon fixation processes were absent but nitrate reduction and denitrification pathways were conserved. The UJ101 genome was compared to genomes from other marine animals (three invertebrate strains and 5 fish strains) and other marine animal- derived genera. Notable results by genome comparisons showed that UJ101 is capable of denitrification and nitrate reduction, and that biotin-thiamine pathway participation varies among marine bacteria; fish-dwelling bacteria, freeliving bacteria, invertebrate-dwelling bacteria, and strain UJ101. Pan-genome analysis of the 16 strains in this study included 7,220 non-redundant genes that covered 62% of the pan-genome. A core-genome of 994 genes was present and consisted of 8% of the genes from the pan-genome. Strain UJ101 is a symbiotic hetero-organotroph isolated from xanthid crab, and is a metabolic generalist with nitrate-reducing abilities but without the ability to synthesize biotin. There is a general tendency of UJ101 and some fish pathogens to prefer thiamine-dependent glycolysis to gluconeogenesis. Biotin and thiamine auxotrophy or prototrophy may be used as important markers in microbial community studies.
Four Arcobacter species have been associated with human disease, and based on current knowledge, these Gram negative bacteria are considered as potential food and waterborne zoonotic pathogens. At present, only the genome of the species Arcobacter butzleri has been analysed, and still little is known about their physiology and genetics. The species Arcobacter thereius has first been isolated from tissue of aborted piglets, duck and pig faeces, and recently from stool of human patients with enteritis. In the present study, the complete genome and analysis of the A. thereius type strain LMG24486T, as well as the comparative genome analysis with 8 other A. thereius strains are presented. Genome analysis revealed metabolic pathways for the utilization of amino acids, which represent the main source of energy, together with the presence of genes encoding for respiration-associated and chemotaxis proteins. Comparative genome analysis with the A. butzleri type strain RM4018 revealed a large correlation, though also unique features. Furthermore, in silico DDH and ANI based analysis of the nine A. thereius strains disclosed clustering into two closely related genotypes. No discriminatory differences in genome content nor phenotypic behaviour were detected, though recently the species Arcobacter porcinus was proposed to encompass part of the formerly identified Arcobacter thereius strains. The report of the presence of virulence associated genes in A. thereius, the presence of antibiotic resistance genes, verified by in vitro susceptibility testing, as well as other pathogenic related relevant features, support the classification of A. thereius as an emerging pathogen.
Xanthomonas citri pv. malvacearum is a major pathogen of cotton, Gossypium hirsutum L.. In this study we report the complete genome of the X. citri pv. malvacearum strain MSCT1 assembled from long read DNA sequencing technology. The MSCT1 genome is the first X. citri pv. malvacearum genome with complete coding regions for X. citri pv. malvacearum transcriptional activator-like effectors. In addition functional and structural annotations are presented in this study that will provide a foundation for future pathogenesis studies with MSCT1.
Lactic acid bacteria play increasingly important roles in the food industry. Streptococcus thermophilus KLDS 3.1003 strain was isolated from traditional yogurt in Inner Mongolia, China. It has shown high antimicrobial activity against selected foodborne and vaginal pathogens. In this study, we investigated and analyzed its complete genome sequence. The S. thermophilus KLDS 3.1003 genome comprise of a 1,899,956 bp chromosome with a G+C content of 38.92%, 1,995 genes, and 6 rRNAs. With the exception of S. thermophilus M17TZA496, S. thermophilus KLDS 3.1003 has more tRNAs (amino acid coding genes) compared to some S. thermophilus strains available on the National Centre for Biotechnology Information database. MG-RAST annotation showed that this strain has 317 subsystems with most genes associated with amino acid and carbohydrate metabolism. This strain also has a unique EPS gene cluster containing 23 genes, and may be a mixed dairy starter culture. This information provides more insight into the molecular basis of its potentials for further applications in the dairy and allied industries.
The soil dwelling actinomycete strain Actinomadura parvosata subsp. kistnae is the producer of the antiviral antibiotics kistamicin A and B. Genome sequencing and bioinformatic analysis revealed the presence of the kistamycin biosynthetic gene cluster responsible for the formation of these non-ribosomal peptides as well as an impressive number of yet uncharacterized biosynthetic pathways. This includes polyketide, ribosomal and non-ribosomal peptide and a large number of terpenoid biosynthetic loci encoding yet unknown natural products. The genomic data of this strain is thus a treasure trove for genome mining for novel functional metabolites and new biocatalysts.
As next generation sequence technology has advanced, there have been parallel advances in genome-scale analysis programs for determining evolutionary relationships as proxies for epidemiological relationship in public health. Most new programs skip traditional steps of ortholog determination and multi-gene alignment, instead identifying variants across a set of genomes, then summarizing results in a matrix of single-nucleotide polymorphisms or alleles for standard phylogenetic analysis. However, public health authorities need to document the performance of these methods with appropriate and comprehensive datasets so they can be validated for specific purposes, e.g., outbreak surveillance. Here we propose a set of benchmark datasets to be used for comparison and validation of phylogenomic pipelines.We identified four well-documented foodborne pathogen events in which the epidemiology was concordant with routine phylogenomic analyses (reference-based SNP and wgMLST approaches). These are ideal benchmark datasets, as the trees, WGS data, and epidemiological data for each are all in agreement. We have placed these sequence data, sample metadata, and “known” phylogenetic trees in publicly-accessible databases and developed a standard descriptive spreadsheet format describing each dataset. To facilitate easy downloading of these benchmarks, we developed an automated script that uses the standard descriptive spreadsheet format.Our “outbreak” benchmark datasets represent the four major foodborne bacterial pathogens (Listeria monocytogenes, Salmonella enterica, Escherichia coli, and Campylobacter jejuni) and one simulated dataset where the “known tree” can be accurately called the “true tree”. The downloading script and associated table files are available on GitHub: https://github.com/WGS-standards-and-analysis/datasets.These five benchmark datasets will help standardize comparison of current and future phylogenomic pipelines, and facilitate important cross-institutional collaborations. Our work is part of a global effort to provide collaborative infrastructure for sequence data and analytic tools-we welcome additional benchmark datasets in our recommended format, and, if relevant, we will add these on our GitHub site. Together, these datasets, dataset format, and the underlying GitHub infrastructure present a recommended path for worldwide standardization of phylogenomic pipelines.
Amoeba-resisting microorganisms raised a great interest during the last decade. Among them, some large DNA viruses present huge genomes up to 2.5?Mb long, exceeding the size of small bacterial genomes. The rate of genome evolution in terms of mutation, deletion, and gene acquisition in these genomes is yet unknown. Given the suspected high plasticity of viral genomes, the microevolution of the 346?kb genome of Lausannevirus, a member of Megavirales, was studied. Hence, Lausannevirus was co-cultured within the amoeba Acanthamoeba castellanii over one year. Despite a low number of mutations, the virus showed a genome reduction of 3.7% after 12?months. Lausannevirus genome evolution in sympatric conditions was investigated by its co-culture with Estrella lausannensis, an obligate intracellular bacterium, in the amoeba A. castellanii during one year. Cultures were split every 3?months. Genome sequencing revealed that in these conditions both, Lausannevirus and E. lausannensis, show stable genome, presenting no major rearrangement. In fact, after one year they acquired from 2 to 7 and from 4 to 10 mutations per culture for Lausannevirus and E. lausannensis, respectively. Interestingly, different mutations in the endonuclease encoding genes of Lausannevirus were observed in different subcultures, highlighting the importance of this gene product in the replication of Lausannevirus. Conversely, mutations in E. lausannensis were mainly located in a gene encoding for a phosphoenolpyruvate-protein phosphotransferase (PtsI), implicated in sugar metabolism. Moreover, in our conditions and with our analyses we detected no horizontal gene transfer during one year of co-culture.© The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
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