Vitreoscilla sp. strain C1 is of historical importance as the source of the first prokaryotic hemoglobin identified. Vitreoscilla spp. rely on their hemoglobin and cytochrome oxidase to grow in microaerobic environments despite their aerobic nature. To help characterize this historically relevant strain, we sequenced the complete Vitreoscilla sp. strain C1 genome.
Methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 8 (CC8) sequence type 239 (ST239) represents a predominant hospital-associated MRSA sublineage present worldwide. The Canadian epidemic MRSA strains CMRSA3 and CMRSA6 are moderately virulent members of this group but are closely related to the highly virulent strain TW20. Whole-genome sequencing of CMRSA3 and CMRSA6 was conducted to identify genetic determinants associated with their virulence.
Carbapenem-resistant Pseudomonas aeruginosa is defined as a textquotedblleftcriticaltextquotedblright priority pathogen for the development of new antibiotics. Here we report the complete genome sequence of an extensively drug-resistant, Verona integron-encoded metallo-ß-lactamase-expressing isolate belonging to the high-risk sequence type 233.
In this report, we present the draft genome sequence of a newly discovered potential probiotic strain of Lactobacillus kefiri, SGL 13, isolated from kefir grains. Antibiotic resistance analysis did not reveal evidence of interspecific horizontal gene transfer since the identified bacitracin resistance gene does not have mobile genetic elements.
We sequenced the genomes of 17 strains isolated from the gut of honey bees, including strains representing the genera Lactobacillus, Bifidobacterium, Gilliamella, Snodgrassella, Frischella, and Commensalibacter. These genome sequences represent an important step forward in the development of a comprehensive reference database to aid future analysis of this emerging gut microbiota model.
Fluoroquinolones (FQs) and ciprofloxacin (Cp) are important antimicrobials that pollute the environment in trace amounts. Although Cp has been recommended as prophylaxis for patients undergoing leech therapy to prevent infections by the leech gut symbiont Aeromonas, a puzzling rise in Cp-resistant (Cpr) Aeromonas infections has been reported. We report on the effects of subtherapeutic FQ concentrations on bacteria in an environmental reservoir, the medicinal leech, and describe the presence of multiple antibiotic resistance mutations and a gain-of-function resistance gene. We link the rise of CprAeromonas isolates to exposure of the leech microbiota to very low levels of Cp (0.01 to 0.04 µg/ml), <1/100 of the clinical resistance breakpoint for Aeromonas Using competition experiments and comparative genomics of 37 strains, we determined the mechanisms of resistance in clinical and leech-derived Aeromonas isolates, traced their origin, and determined that the presence of merely 0.01 µg/ml Cp provides a strong competitive advantage for Cpr strains. Deep-sequencing the Cpr-conferring region of gyrA enabled tracing of the mutation-harboring Aeromonas population in archived gut samples, and an increase in the frequency of the Cpr-conferring mutation in 2011 coincides with the initial reports of CprAeromonas infections in patients receiving leech therapy.IMPORTANCE The role of subtherapeutic antimicrobial contamination in selecting for resistant strains has received increasing attention and is an important clinical matter. This study describes the relationship of resistant bacteria from the medicinal leech, Hirudo verbana, with patient infections following leech therapy. While our results highlight the need for alternative antibiotic therapies, the rise of Cpr bacteria demonstrates the importance of restricting the exposure of animals to antibiotics approved for veterinary use. The shift to a more resistant community and the dispersion of Cpr-conferring mechanisms via mobile elements occurred in a natural setting due to the presence of very low levels of fluoroquinolones, revealing the challenges of controlling the spread of antibiotic-resistant bacteria and highlighting the importance of a holistic approach in the management of antibiotic use. Copyright © 2018 Beka et al.
At least five gene clusters in the Geobacter sulfurreducens genome encode putative “electron conduits” implicated in electron transfer across the outer membrane, each containing a periplasmic multiheme c-type cytochrome, integral outer membrane anchor, and outer membrane redox lipoprotein(s). Markerless single-gene-cluster deletions and all possible multiple-deletion combinations were constructed and grown with soluble Fe(III) citrate, Fe(III) and Mn(IV) oxides, and graphite electrodes poised at +0.24 V and -0.1 V versus the standard hydrogen electrode (SHE). Different gene clusters were necessary for reduction of each electron acceptor. During metal oxide reduction, deletion of the previously described omcBC cluster caused defects, but deletion of additional components in an ?omcBC background, such as extEFG, were needed to produce defects greater than 50% compared to findings with the wild type. Deletion of all five gene clusters abolished all metal reduction. During electrode reduction, only the ?extABCD mutant had a severe growth defect at both redox potentials, while this mutation did not affect Fe(III) oxide, Mn(IV) oxide, or Fe(III) citrate reduction. Some mutants containing only one cluster were able to reduce particular terminal electron acceptors better than the wild type, suggesting routes for improvement by targeting specific electron transfer pathways. Transcriptomic comparisons between fumarate and electrode-based growth conditions showed all of these ext clusters to be constitutive, and transcriptional analysis of the triple-deletion strain containing only extABCD detected no significant changes in expression of genes encoding known redox proteins or pilus components. These genetic experiments reveal new outer membrane conduit complexes necessary for growth of G. sulfurreducens, depending on the available extracellular electron acceptor.IMPORTANCE Gram-negative metal-reducing bacteria utilize electron conduits, chains of redox proteins spanning the outer membrane, to transfer electrons to the extracellular surface. Only one pathway for electron transfer across the outer membrane of Geobacter sulfurreducens has been linked to Fe(III) reduction. However, G. sulfurreducens is able to respire a wide array of extracellular substrates. Here we present the first combinatorial genetic analysis of five different electron conduits via creation of new markerless deletion strains and complementation vectors. Multiple conduit gene clusters appear to have overlapping roles, including two that have never been linked to metal reduction. Another recently described cluster (ExtABCD) was the only electron conduit essential during electrode reduction, a substrate of special importance to biotechnological applications of this organism. Copyright © 2018 Jiménez Otero et al.
For their food source, Trachymyrmex septentrionalis ants raise symbiotic fungus gardens that contain bacteria whose functions are poorly understood. Here, we report the genome sequences of eight bacteria isolated from these fungus gardens to better describe the ecology of these strains and their potential to produce secondary metabolites in this niche.
Nontypeable Haemophilus influenzae (NTHi) is an important bacterial pathogen that causes otitis media and exacerbations of chronic obstructive pulmonary disease (COPD). Here, we report the complete genome sequences of NTHi strains 10P129H1 and 84P36H1, isolated from COPD patients, which contain the phase-variable epigenetic regulators ModA15 and ModA18, respectively.
The genus Methanosphaera is a well-recognized but poorly characterized member of the mammalian gut microbiome, and distinctive from Methanobrevibacter smithii for its ability to induce a pro-inflammatory response in humans. Here we have used a combination of culture- and metagenomics-based approaches to expand the representation and information for the genus, which has supported the examination of their phylogeny and physiological capacity. Novel isolates of the genus Methanosphaera were recovered from bovine rumen digesta and human stool, with the bovine isolate remarkable for its large genome size relative to other Methanosphaera isolates from monogastric hosts. To substantiate this observation, we then recovered seven high-quality Methanosphaera-affiliated population genomes from ruminant and human gut metagenomic datasets. Our analyses confirm a monophyletic origin of Methanosphaera spp. and that the colonization of monogastric and ruminant hosts favors representatives of the genus with different genome sizes, reflecting differences in the genome content needed to persist in these different habitats.
The Mobile Genetic Elements and Genome Plasticity conference was hosted by Keystone Symposia in Santa Fe, NM USA, February 11–15, 2018. The organizers were Marlene Belfort, Evan Eichler, Henry Levin and Lynn Maquat. The goal of this conference was to bring together scientists from around the world to discuss the function of transposable elements and their impact on host species. Central themes of the meeting included recent innovations in genome analysis and the role of mobile DNA in disease and evolution. The conference included 200 scientists who participated in poster presentations, short talks selected from abstracts, and invited talks. A total of 58 talks were organized into eight sessions and two workshops. The topics varied from mechanisms of mobilization, to the structure of genomes and their defense strategies to protect against transposable elements.
Long-read sequencing technologies are the ultimate solution for genome repeats, allowing near reference-level reconstructions of large genomes. However, long-read de novo assembly pipelines are computationally intense and require a considerable amount of coverage, thereby hindering their broad application to the assembly of large genomes. Alternatively, hybrid assembly methods that combine short- and long-read sequencing technologies can reduce the time and cost required to produce de novo assemblies of large genomes.Here, we propose a new method, called Fast-SG, that uses a new ultrafast alignment-free algorithm specifically designed for constructing a scaffolding graph using light-weight data structures. Fast-SG can construct the graph from either short or long reads. This allows the reuse of efficient algorithms designed for short-read data and permits the definition of novel modular hybrid assembly pipelines. Using comprehensive standard datasets and benchmarks, we show how Fast-SG outperforms the state-of-the-art short-read aligners when building the scaffoldinggraph and can be used to extract linking information from either raw or error-corrected long reads. We also show how a hybrid assembly approach using Fast-SG with shallow long-read coverage (5X) and moderate computational resources can produce long-range and accurate reconstructions of the genomes of Arabidopsis thaliana (Ler-0) and human (NA12878).Fast-SG opens a door to achieve accurate hybrid long-range reconstructions of large genomes with low effort, high portability, and low cost.
Root-knot nematodes (Meloidogyne spp.) cause serious damage to many crops globally. We report the high-quality genome sequence of Meloidogyne arenaria genotype A2-O. The genome assembly of M. arenaria A2-O is composed of 2,224 contigs with an N50 contig length of 204,551?bp and a total assembly length of 284.05?Mb. Copyright © 2018 Sato et al.
Acinetobacter schindleri strain SGAir0122 was isolated from tropical air samples collected in Singapore. The prevalence of nosocomial infection caused by this Gram-negative bacterium indicates its clinical significance as an opportunistic human pathogen. Its complete genome consists of one chromosome of 3.105?Mb and a plasmid of 181?kb. Copyright © 2018 Kee et al.
Carbapenems are an important class of ß-lactams and one of the last options for treating severe human infections. We present here the complete genome sequence of avian native carbapenemase-producing Salmonella enterica subsp. enterica serovar Corvallis strain 12-01738, harboring a blaNDM-1-carrying IncA/C2 plasmid, isolated in 2012 from a wild bird (Milvus migrans) in Germany. Copyright © 2018 Hadziabdic et al.
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