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Asset Tag: Bacterial genome

April 21, 2020

Gramella fulva sp. nov., isolated from a dry surface of tidal flat.

A novel Gram-stain-negative, aerobic, motile by means of gliding, and short rod-shaped bacterium, designated strain SH35T, was isolated from the dry surface of a tidal flat in Hwasung-si, South Korea. Growth occurred at 10-40°C (optimum 30°C), at pH 6.0-8.0 (optimum pH 7.0), in 1-12% NaCl (optimum 2%), and was inhibited in the absence of NaCl and Ca2+ ions. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain SH35T belonged to the genus Gramella and was a member of the family Flavobacteriaceae with highest sequence similarity to Gramella flava JLT2011T (96.1%), followed by Gramella oceani CCAMSZ-TT (95.6%), and 93.0-94.9% to other recognized Gramella species. The major cellular fatty acids (> 5% of the total) of strain SH35T were iso-C15:0, Iso-C16:0, anteiso-C15:0, iso-C17:0 3-OH and summed feature 9 (C16:0 10-methyl and/or C17:1 iso ?9?). The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids and nine unidentified polar lipids. The major respiratory quinone and the predominant polyamine were menaquinone-6 (MK-6) and symhomospermidine, respectively. The DNA G + C content was 40.5 mol% (39.7% based on total genome calculations). Based on phylogenetic analysis and physiological and biochemical characterization, strain SH35T represents a novel species of the genus Gramella, for which the name Gramella fulva sp. nov. is proposed. The type strain is SH35T (= KACC 19447T = JCM 32369T).

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April 21, 2020

Complete Genome Sequence of Saccharospirillum mangrovi HK-33T Sheds Light on the Ecological Role of a Bacterium in Mangrove Sediment Environment.

We present the genome sequence of Saccharospirillum mangrovi HK-33T, isolated from a mangrove sediment sample in Haikou, China. The complete genome of S. mangrovi HK-33T consisted of a single-circular chromosome with the size of 3,686,911 bp as well as an average G?+?C content of 57.37%, and contained 3,383 protein-coding genes, 4 operons of 16S-23S-5S rRNA genes, and 52 tRNA genes. Genomic annotation indicated that the genome of S. mangrovi HK-33T had many genes related to oligosaccharide and polysaccharide degradation and utilization of polyhydroxyalkanoate. For nitrogen cycle, genes encoding nitrate and nitrite reductase, glutamate dehydrogenase, glutamate synthase, and glutamine synthetase could be found. For phosphorus cycle, genes related to polyphosphate kinases (ppk1 and ppk2), the high-affinity phosphate-specific transport (Pst) system, and the low-affinity inorganic phosphate transporter (pitA) were predicted. For sulfur cycle, cysteine synthase and type III acyl coenzyme A transferase (dddD) coding genes were searched out. This study provides evidence about carbon, nitrogen, phosphorus, and sulfur metabolic patterns of S. mangrovi HK-33T and broadens our understandings about ecological roles of this bacterium in the mangrove sediment environment.

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April 21, 2020

Liquid-Infused Structured Titanium Surfaces: Antiadhesive Mechanism to Repel Streptococcus oralis Biofilms.

To combat implant-associated infections, there is a need for novel materials which effectively inhibit bacterial biofilm formation. In the present study, the antiadhesive properties of titanium surface functionalization based on the “slippery liquid-infused porous surfaces” (SLIPS) principle were demonstrated and the underlying mechanism was analyzed. The immobilized liquid layer was stable over 13 days of continuous flow in an oral flow chamber system. With increasing flow rates, the surface exhibited a significant reduction in attached biofilm of both the oral initial colonizer  Streptococcus oralis and an oral multispecies biofilm composed of S. oralis, Actinomyces naeslundii, Veillonella dispar, and Porphyromonas gingivalis. Using single cell force spectroscopy, reduced S. oralis adhesion forces on the lubricant layer could be measured. Gene expression patterns in biofilms on SLIPS, on control surfaces, and expression patterns of planktonic cultures were also compared. For this purpose, the genome of S. oralis strain ATCC 9811 was sequenced using PacBio Sequel technology. Even though biofilm cells showed clear changes in gene expression compared to planktonic cells, no differences could be detected between bacteria on SLIPS and on control surfaces. Therefore, it can be concluded that the ability of liquid-infused titanium to repel S. oralis biofilms is mainly due to weakened bacterial adhesion to the underlying liquid interface.

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April 21, 2020

Antarctic heterotrophic bacterium Hymenobacter nivis P3T displays light-enhanced growth and expresses putative photoactive proteins.

Hymenobacter nivis P3T is a heterotrophic bacterium isolated from Antarctic red snow generated by algal blooms. Despite being non-photosynthetic, H. nivis was dominantly found in the red snow environment that is exposed to high light and UV irradiation, suggesting that this species can flourish under such harsh conditions. In order to further understand the adaptive strategies on the snow surface environment of Antarctica, the genome of H. nivis P3T was sequenced and analyzed, which identified genes putatively encoding for light-reactive proteins such as proteorhodopsin, phytochrome, photolyase and several copies of cryptochromes. Culture-based experiments revealed that H. nivis P3T growth was significantly enhanced under light conditions, while dark conditions had increased extracellular polymeric substances. Furthermore, the expression of several putative light-reactive proteins was determined by proteomic analysis. These results indicate that H. nivis P3T is able to potentially utilize light, which may explain its dominance on the red snow surface environment of Antarctica. ORIGINALITY-SIGNIFICANCE STATEMENT: The role of proteorhodopsin in heterotrophic bacteria is not well-characterized, as only a handful of proteorhodopsin-harbouring isolates were shown to have a light-enhanced phenotype through culture-based experiments to date. This is the first study that demonstrates light-stimulated growth and protein expression evidence of photoactive proteins for a non-marine psychrophile and for a member of the genus Hymenobacter. It is also the first study that provides comprehensive proteome information for this genus. This study presents significant results in understanding the adaptive mechanism of a heterotrophic non-photosynthetic bacterium thriving on the snow surface environment of Antarctica as well as demonstrating the role of light-utilization in promoting growth, possibly through proteorhodopsin. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

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April 21, 2020

Characterization of NDM-5- and CTX-M-55-coproducing Escherichia coli GSH8M-2 isolated from the effluent of a wastewater treatment plant in Tokyo Bay.

New Delhi metallo-ß-lactamase (NDM)-5-producing Enterobacteriaceae have been detected in rivers, sewage, and effluents from wastewater treatment plants (WWTPs). Environmental contamination due to discharged effluents is of particular concern as NDM variants may be released into waterways, thereby posing a risk to humans. In this study, we collected effluent samples from a WWTP discharged into a canal in Tokyo Bay, Japan.Testing included the complete genome sequencing of Escherichia coli GSH8M-2 isolated from the effluent as well as a gene network analysis.The complete genome sequencing of GSH8M-2 revealed that it was an NDM-5-producing E. coli strain sequence type ST542, which carries multiple antimicrobial resistance genes for ß-lactams, quinolone, tetracycline, trimethoprim-sulfamethoxazole, florfenicol/chloramphenicol, kanamycin, and fosfomycin. The blaNDM-5 gene was found in the IncX3 replicon plasmid pGSH8M-2-4. Gene network analysis using 142 IncX3 plasmid sequences suggested that pGSH8M-2-4 is related to both clinical isolates of  E. coli and Klebsiella species in Eastern Asia. GSH8M-2 also carries the blaCTX-M-55 gene in IncX1 plasmid pGSH8M-2-3.This is the first report of environmental NDM-5-producing E. coli isolated from a WWTP in Japan. NDM-5 detection is markedly increasing in veterinary and clinical settings, suggesting that dual ß-lactamases, such as NDM-5 and CTX-M-55, might be acquired through multiple steps in environment settings. Environmental contamination through WWTP effluents that contain producers of NDM variants could be an emerging potential health hazard. Thus, regular monitoring of WWTP effluents is important for the detection of antimicrobial-resistant bacteria that may be released into the waterways and nearby communities.

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April 21, 2020

Genomic analysis of three Clostridioides difficile isolates from urban water sources.

We investigated inflow of a wastewater treatment plant and sediment of an urban lake for the presence of Clostridioides difficile by cultivation and PCR. Among seven colonies we sequenced the complete genomes of three: two non-toxigenic isolates from wastewater and one toxigenic isolate from the urban lake. For all obtained isolates, a close genomic relationship with human-derived isolates was observed.Copyright © 2019 Elsevier Ltd. All rights reserved.

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April 21, 2020

Geography Shapes the Population Genomics of Salmonella enterica Dublin.

Salmonella enterica serotype Dublin (S. Dublin) is a bovine-adapted serotype that can cause serious systemic infections in humans. Despite the increasing prevalence of human infections and the negative impact on agricultural processes, little is known about the population structure of the serotype. To this end, we compiled a manually curated data set comprising of 880 S. Dublin genomes. Core genome phylogeny and ancestral state reconstruction revealed that region-specific clades dominate the global population structure of S. Dublin. Strains of S. Dublin in the UK are genomically distinct from US, Brazilian, and African strains. The geographical partitioning impacts the composition of the core genome as well as the ancillary genome. Antibiotic resistance genes are almost exclusively found in US genomes and are mediated by an IncA/C2 plasmid. Phage content and the S. Dublin virulence plasmid were strongly conserved in the serotype. Comparison of S. Dublin to a closely related serotype, S. enterica serotype Enteritidis, revealed that S. Dublin contains 82 serotype specific genes that are not found in S. Enteritidis. Said genes encode metabolic functions involved in the uptake and catabolism of carbohydrates and virulence genes associated with type VI secretion systems and fimbria assembly respectively. © The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

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April 21, 2020

Biomimetic hydroxyapatite nanocrystals are an active carrier for Salmonella bacteriophages.

The use of bacteriophages represents a valid alternative to conventional antimicrobial treatments, overcoming the widespread bacterial antibiotic resistance phenomenon. In this work, we evaluated whether biomimetic hydroxyapatite (HA) nanocrystals are able to enhance some properties of bacteriophages. The final goal of this study was to demonstrate that biomimetic HA nanocrystals can be used for bacteriophage delivery in the context of bacterial infections, and contribute – at the same time – to enhance some of the biological properties of the same bacteriophages such as stability, preservation, antimicrobial activity, and so on.Phage isolation and characterization were carried out by using Mitomycin C and following double-layer agar technique. The biomimetic HA water suspension was synthesized in order to obtain nanocrystals with plate-like morphology and nanometric dimensions. The interaction of phages with the HA was investigated by dynamic light scattering and Zeta potential analyses. The cytotoxicity and intracellular killing activities of the phage-HA complex were evaluated in human hepatocellular carcinoma HepG2 cells. The bacterial inhibition capacity of the complex was assessed on chicken minced meat samples infected with Salmonella Rissen.Our data highlighted that the biomimetic HA nanocrystal-bacteriophage complex was more stable and more effective than phages alone in all tested experimental conditions.Our results evidenced the important contribution of biomimetic HA nanocrystals: they act as an excellent carrier for bacteriophage delivery and enhance its biological characteristics. This study confirmed the significant role of the mineral HA when it is complexed with biological entities like bacteriophages, as it has been shown for molecules such as lactoferrin.

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April 21, 2020

Characterization of a novel, type II staphylococcal cassette chromosome mec element from an endemic oxacillin-resistant Staphylococcus lugdunensis clone in a hospital setting.

Staphylococcus lugdunensis is a significant pathogen that causes community-acquired and nosocomial infections. The high prevalence of oxacillin-resistant S. lugdunensis (ORSL) is of major concern. Resistance to ß-lactams is caused by acquisition of the staphylococcal cassette chromosome mec (SCCmec) element. The cassette is highly diverse, both structurally and genetically, among CoNS. Isolates carrying SCCmec II-ST6 are the major persistent clones in hospitals.To investigate the structure and evolutionary origin of a novel type II SCCmec element in an endemic ST6 S. lugdunensis clone.The structure of the SCCmec II element carried by ST6 strain CGMH-SL118 was determined by WGS and compared with those reported previously.A novel 39 kb SCCmec element, SCCmecCGMH-SL118, with a unique mosaic structure comprising 41 ORFs integrated into the 3′ end of the rlmH gene, was observed. Some regions of SCCmecCGMH-SL118 were homologous to SCCmec IIa of the prototype MRSA strain N315. The structure of SCCmecCGMH-SL118 was similar to that of SCCmec IIb of the MRSA strain, JCSC3063, mainly lacking the aminoglycoside resistance determinant pUB110 in the J3 region but containing the insertion sequence IS256 in the J2 region. Notably, SCCmecCGMH-SL118 deletions in the J1 region compared with SCCmec types IIa and IIb, and a high homology to SCCmec elements of Staphylococcus aureus JCSC4610 and Staphylococcus haemolyticus strain 621 were found.The genetic diversity of the type II SCCmec element in ORSL suggests that CoNS is a potential reservoir for interspecies transfer of SCCmec to S. aureus in hospitals. © The Author(s) 2019. 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.

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April 21, 2020

The first report of a novel IncHI1B blaSIM-1-carrying megaplasmid pSIM-1-BJ01 from a clinical Klebsiella pneumoniae isolate.

Background: A rare member of metallo-ß-lactamases genes, blaSIM-1, carried by a 316-kb plasmid designated pSIM-1-BJ01 was isolated from a clinical cephalosporins- and carbapenem-resistant Klebsiellapneumoniae 13624. This is the first sequence report of a transferable blaSIM-1-carrying conjugative plasmid isolated from K. pneumoniae. Purpose: The sequence analysis of pSIM-1-BJ01 will help us to identify genes responsible for conjugation, plasmid maintenance and drug resistance, to understand the evolution and control the dissemination of resistance plasmids. Patients and methods:K. pneumoniae 13624 was isolated from the urine specimen of a patient. Bacterial genomic DNA was sequenced with PacBio RSII platform. Results: Most of the pSIM-1-BJ01 backbone matches that of pRJA166a, which was isolated from a clinical hypervirulent K. pneumoniae ST23 strain at Shanghai, China, recently. The highly homologous backbones between the two plasmids imply the close relationship of evolution. Two different multidrug-resistant regions both carrying the class 1 integrons with different resistance genes have been assembled into the pSIM-1-BJ01. Besides, the other two resistance plasmids, pKP13624-1 carrying blaTEM-1 and blaCTX-M-15 and pKP13624-2 carrying blaCTX-M-14 and blaLAP-2 were also identified. Conclusion: The emergence of the blaSIM-1-carrying IncHI1B pSIM-1-BJ01 suggests the spread of blaSIM among Enterobacteriaceae is possible. We should pay more attention to supervise and control the dissemination of hypervirulent carbapenem-resistant K. pneumonia in public hospitals.

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April 21, 2020

Genome characterization of an extensively drug-resistant Streptococcus pneumoniae serotype 11A strain.

In this study, the whole genome sequences of two Streptococcus pneumoniae clinical isolates from South Korea were determined and compared. They were found to be the same serotype (11?A) and multilocus sequence typing analysis showed that they are single-locus variants (SLVs; ST8279 and ST166) of each other, differing at one allele (aroE). However, the ST8279 strain is extensively drug-resistant (XDR) whereas the ST166 strain is not. The genome of the XDR strain is very similar in structure to that of two previously reported genomes, AP200 (11?A:ST62) and 70585 (5:ST5803); however, some regions were inverted and there were some exogenous regions in the ST8279 strain. It was found that 6,502 single nucleotide polymorphisms are dispersed across the genome between the two serotype 11?A ST8279 and ST166 strains. Many of them are located in genes associated with antibiotic resistance. In addition, many amino acid differences were also identified in genes involved in DNA repair (mutL, uvrA and uvrC) and recombination (recU, recR and recA). On the basis of these results, it was inferred that the XDR strain did not evolve from its SLV via a single recombination event involving a large portion of the genome including the aroE gene. Rather, the strain likely evolved through many point mutations and recombination events involving small portions of the genome. © 2019 The Societies and John Wiley & Sons Australia, Ltd.

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April 21, 2020

Genetic, structural, and functional diversity of low and high-affinity siderophores in strains of nitrogen fixing Azotobacter chroococcum.

To increase iron (Fe) bioavailability in surface soils, microbes secrete siderophores, chelators with widely varying Fe affinities. Strains of the soil bacterium Azotobacter chroococcum (AC), plant-growth promoting rhizobacteria used as agricultural inoculants, require high Fe concentrations for aerobic respiration and nitrogen fixation. Recently, A. chroococcum str. NCIMB 8003 was shown to synthesize three siderophore classes: (1) vibrioferrin, a low-affinity a-hydroxy carboxylate (pFe = 18.4), (2) amphibactins, high-affinity tris-hydroxamates, and (3) crochelin A, a high-affinity siderophore with mixed Fe-chelating groups (pFe = 23.9). The relevance and specific functions of these siderophores in AC strains remain unclear. We analyzed the genome and siderophores of a second AC strain, A. chroococcum str. B3, and found that it also produces vibrioferrin and amphibactins, but not crochelin A. Genome comparisons indicate that vibrioferrin production is a vertically inherited, conserved strategy for Fe uptake in A. chroococcum and other species of Azotobacter. Amphibactin and crochelin biosynthesis reflects a more complex evolutionary history, shaped by vertical gene transfer, gene gain and loss through recombination at a genomic hotspot. We found conserved patterns of low vs. high-affinity siderophore production across strains: the low-affinity vibrioferrin was produced by mildly Fe limited cultures. As cells became more severely Fe starved, vibrioferrin production decreased in favor of high-affinity amphibactins (str. B3, NCIMB 8003) and crochelin A (str. NCIMB 8003). Our results show the evolution of low and high-affinity siderophore families and conserved patterns for their production in response to Fe bioavailability in a common soil diazotroph.

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April 21, 2020

Evolution of Klebsiella pneumoniae with mucoid and non-mucoid type colonies within a single patient.

We obtained nine Klebsiella pneumoniae isolates successively isolated from a single patient. Four pairs (M1-M4 and NM1-NM4) obtained simultaneously from the same site showed different colony types, mucoid and non-mucoid, while the final isolate (M5) was isolated alone from the blood and showed a mucoid phenotype. The whole genome of isolate M5 was sequenced de novo using the PacBio RSII system, while the others were sequenced with an Illumina Hiseq4000 and mapped to the genome sequences of M5. To identify insertions or deletions in the cps locus, we amplified and sequenced cps locus genes. We identified insertion sequence (IS) elements in several genes of the cps locus or one amino acid substitution in WcaJ in all non-mucoid isolates. Five additional amino acid alterations in RpsJ, LolE, Lon-2, PpsE, and a hypothetical protein were detected in some mucoid and non-mucoid isolates. Based on the genome data and cps locus sequences, the mucoid phenotype may have been lost or converted into the non-mucoid phenotype because of the insertion of IS elements or amino acid alterations at this locus. We inferred a within-host evolutionary scenario, in which non-mucoid variants emerged repeatedly from mucoid isolates, but may be short-lived because of their low fitness.Copyright © 2019 Elsevier GmbH. All rights reserved.

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April 21, 2020

Tengunoibacter tsumagoiensis gen. nov., sp. nov., Dictyobacter kobayashii sp. nov., Dictyobacter alpinus sp. nov., and description of Dictyobacteraceae fam. nov. within the order Ktedonobacterales isolated from Tengu-no-mugimeshi, a soil-like granular mass of micro-organisms, and emended descriptions of the genera Ktedonobacter and Dictyobacter.

Three mesophilic, Gram-stain-positive, aerobic bacterial strains, designated Uno3T, Uno11T and Uno16T, were isolated from a soil-like granular micro-organism mass (termed Tengu-no-mugimeshi) collected from Tsumagoi, Gunma, Japan. They grow at 11-37?°C?and pH 4.0-8.0, form branched mycelia, and have a G+C?content between 49.4-50.3?mol%. The major menaquinone and fatty acid of Uno3T are MK-9 and iso-C16?:?0, respectively, whereas Uno11T and Uno16T share MK-9 (H2) and C16?:?1-2OH. The major cell-wall sugars are mannose (Uno3T and Uno11T) and glucose (Uno16T). Phylogenetic analysis based on 16S rRNA gene sequences indicated that these three strains belong to the order Ktedonobacterales and are most closely related to Dictyobacter aurantiacus S-27T (sequence similarity of 91.3, 96.4 and 95.5?%). Average nucleotide identity values were <79.9?% among Uno11T, Uno16T and D. aurantiacus S-27T, well below the 95-96?%?species circumscription threshold. Based on phenotypic features and phylogenetic positions, we propose that Uno3T represents a novel genus and species, Tengunoibacter tsumagoiensis gen. nov., sp. nov. (type strain Uno3T=NBRC 113152T=LMG 30471T=BCRC 81113T) within the new family Dictyobacteraceae fam. nov. Strains Uno11T and Uno16T are also considered to represent novel species: Dictyobacterkobayashii sp. nov. (type strain Uno11T=NBRC 113153T=LMG 30472T=BCRC 81114T) and Dictyobacteralpinus sp. nov. (type strain Uno16T=NBRC 113154T=BCRC 81115T). We also propose an emended description of the genus Dictyobacter, classifying it within family Dictyobacteraceae, and provide emended descriptions of the genera Dictyobacter and Ktedonobacter.

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April 21, 2020

Dissemination of multiple carbapenem resistance genes in an in vitro gut model simulating the human colon.

Carbapenemase-producing Enterobacteriaceae (CPE) pose a major global health risk. Mobile genetic elements account for much of the increasing CPE burden.To investigate CPE colonization and the impact of antibiotic exposure on subsequent resistance gene dissemination within the gut microbiota using a model to simulate the human colon.Gut models seeded with CPE-negative human faeces [screened with BioMérieux chromID® CARBA-SMART (Carba-Smart), Cepheid Xpert® Carba-R assay (XCR)] were inoculated with distinct carbapenemase-producing Klebsiella pneumoniae strains (KPC, NDM) and challenged with imipenem or piperacillin/tazobactam then meropenem. Resistant populations were enumerated daily on selective agars (Carba-Smart); CPE genes were confirmed by PCR (XCR, Check-Direct CPE Screen for BD MAX™). CPE gene dissemination was tracked using PacBio long-read sequencing.CPE populations increased during inoculation, plateauing at ~105?log10?cfu/mL in both models and persisting throughout the experiments (>65?days), with no evidence of CPE ‘washout’. After antibiotic administration, there was evidence of interspecies plasmid transfer of blaKPC-2 (111742?bp IncFII/IncR plasmid, 99% identity to pKpQIL-D2) and blaNDM-1 (~170?kb IncFIB/IncFII plasmid), and CPE populations rose from <0.01% to >45% of the total lactose-fermenting populations in the KPC model. Isolation of a blaNDM-1K. pneumoniae with one chromosomal single-nucleotide variant compared with the inoculated strain indicated clonal expansion within the model. Antibiotic administration exposed a previously undetected K. pneumoniae encoding blaOXA-232 (KPC model).CPE exposure can lead to colonization, clonal expansion and resistance gene transfer within intact human colonic microbiota. Furthermore, under antibiotic selective pressure, new resistant populations emerge, emphasizing the need to control exposure to antimicrobials. © The Author(s) 2019. 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.

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