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July 7, 2019  |  

Genome sequence of Pseudomonas citronellolis SJTE-3, an estrogen- and polycyclic aromatic hydrocarbon-degrading bacterium.

Pseudomonas citronellolis SJTE-3, isolated from the active sludge of a wastewater treatment plant in China, can utilize a series of environmental estrogens and estrogen-like toxicants. Here, we report its whole-genome sequence, containing one circular chromosome and one circular plasmid. Genes involved in estrogen biodegradation in this bacterium were predicted. Copyright © 2016 Zheng et al.


July 7, 2019  |  

The draft genome of whitefly Bemisia tabaci MEAM1, a global crop pest, provides novel insights into virus transmission, host adaptation, and insecticide resistance.

The whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is among the 100 worst invasive species in the world. As one of the most important crop pests and virus vectors, B. tabaci causes substantial crop losses and poses a serious threat to global food security. We report the 615-Mb high-quality genome sequence of B. tabaci Middle East-Asia Minor 1 (MEAM1), the first genome sequence in the Aleyrodidae family, which contains 15,664 protein-coding genes. The B. tabaci genome is highly divergent from other sequenced hemipteran genomes, sharing no detectable synteny. A number of known detoxification gene families, including cytochrome P450s and UDP-glucuronosyltransferases, are significantly expanded in B. tabaci. Other expanded gene families, including cathepsins, large clusters of tandemly duplicated B. tabaci-specific genes, and phosphatidylethanolamine-binding proteins (PEBPs), were found to be associated with virus acquisition and transmission and/or insecticide resistance, likely contributing to the global invasiveness and efficient virus transmission capacity of B. tabaci. The presence of 142 horizontally transferred genes from bacteria or fungi in the B. tabaci genome, including genes encoding hopanoid/sterol synthesis and xenobiotic detoxification enzymes that are not present in other insects, offers novel insights into the unique biological adaptations of this insect such as polyphagy and insecticide resistance. Interestingly, two adjacent bacterial pantothenate biosynthesis genes, panB and panC, have been co-transferred into B. tabaci and fused into a single gene that has acquired introns during its evolution.The B. tabaci genome contains numerous genetic novelties, including expansions in gene families associated with insecticide resistance, detoxification and virus transmission, as well as numerous horizontally transferred genes from bacteria and fungi. We believe these novelties likely have shaped B. tabaci as a highly invasive polyphagous crop pest and efficient vector of plant viruses. The genome serves as a reference for resolving the B. tabaci cryptic species complex, understanding fundamental biological novelties, and providing valuable genetic information to assist the development of novel strategies for controlling whiteflies and the viruses they transmit.


July 7, 2019  |  

Epigenetic mechanisms in microbial members of the human microbiota: current knowledge and perspectives.

The human microbiota and epigenetic processes have both been shown to play a crucial role in health and disease. However, there is extremely scarce information on epigenetic modulation of microbiota members except for a few pathogens. Mainly DNA adenine methylation has been described extensively in modulating the virulence of pathogenic bacteria in particular. It would thus appear likely that such mechanisms are widespread for most bacterial members of the microbiota. This review will present briefly the current knowledge on epigenetic processes in bacteria, give examples of known methylation processes in microbial members of the human microbiota and summarize the knowledge on regulation of host epigenetic processes by the human microbiota.


July 7, 2019  |  

Scoping the effectiveness and evolutionary obstacles in using plasmid-dependent phages to fight antibiotic resistance.

To investigate the potential evolutionary obstacles in the sustainable therapeutic use of plasmid-dependent phages to control the clinically important conjugative plasmid-mediated dissemination of antibiotic resistance genes to pathogenic bacteria.The lytic plasmid-dependent phage PRD1 and the multiresistance conferring plasmid RP4 in an Escherichia coli host were utilized to assess the genetic and phenotypic changes induced by combined phage and antibiotic selection.Resistance to PRD1 was always coupled with either completely lost or greatly reduced conjugation ability. Reversion to full conjugation efficiency was found to be rare, and it also restored the susceptibility to plasmid-dependent phages. Consequently, plasmid-dependent phages constitute an interesting candidate for development of sustainable anticonjugation/antiresistance therapeutic applications.


July 7, 2019  |  

Genomics-inspired discovery of three antibacterial active metabolites, aurantinins B, C, and D from compost-associated Bacillus subtilis fmb60.

Fmb60 is a wild-type Bacillus subtilis isolated from compost with significant broad-spectrum antimicrobial activities. Two novel PKS clusters were recognized in the genome sequence of fmb60, and then three polyene antibiotics, aurantinins B, C, and D, 1-3, were obtained by bioactivity-guided isolation from the fermentation of fmb60. The structures of aurantinins B-D were elucidated by LC-HRMS and NMR data analysis. Aurantinins C and D were identified as new antimicrobial compounds. The three aurantinins showed significant activity against multidrug-resistant Staphylococcus aureus and Clostridium sporogenes. However, aurantinins B-D did not exhibit any cytotoxicity (IC50 > 100 µg/mL) against LO2 and Caco2 cell lines by MTT assay. Furthermore, using S. aureus as a model bacterium to explore the antibacterial mechanism of aurantinins B-D, it was revealed that the bactericidal activity of aurantinins B-D was related to their ability to disrupt the cell membrane.


July 7, 2019  |  

Genomic and transcriptomic analyses reveal the characterization of a crude oil degrading bacterial strain: Pedobacter steynii DX4

Pedobacter steynii DX4, isolated from Qinghai-Tibet plateau, exhibited capability to effectively degrade crude oil at low temperature. In order to illustrate its biodegradation mechanism, whole genome and transcriptome sequencing were performed. It is the first genome of crude oil degrading strain in Pedobacter genus. The P. steynii DX4 genome consists of a single circular chromosome of 6,581,659 bp with an average G+C content of 41.31% and encodes 5464 genes in all. GIs were predicted and comparison analysis was performed between relative species. Genome annotation predicted several hydrocarbon oxygenases, chemotaxis proteins and biosurfactant synthetases. The transcriptional sequences profiled a lot of differently expressed genes when cells respectively grown on crude oil and pyruvate mediums. Crude oil significantly stimulated the expression of the genes related to the hydrocarbon oxidation and resparitory chain. Genomic and transcriptomic analysis of P. steynii DX4 have revealed the machenism of the crude oil degradation in Pedobacter steynii DX4 and provided us with valuable knowledge base to make effective strategy to mitigate the ecological damage caused by crude oil pollution.


July 7, 2019  |  

Characterization of tet(Y)-carrying LowGC plasmids exogenously captured from cow manure at a conventional dairy farm.

Manure from dairy farms has been shown to contain diverse tetracycline resistance genes that are transferable to soil. Here, we focus on conjugative plasmids that may spread tetracycline resistance at a conventional dairy farm. We performed exogenous plasmid isolation from cattle feces using chlortetracycline for transconjugant selection. The transconjugants obtained harbored LowGC-type plasmids and tet(Y). A representative plasmid (pFK2-7) was fully sequenced and this was compared with previously described LowGC plasmids from piggery manure-treated soil and a GenBank record from Acinetobacter nosocomialis that we also identified as a LowGC plasmid. The pFK2-7 plasmid had the conservative backbone typical of LowGC plasmids, though this region was interrupted with an insert containing the tet(Y)-tet(R) tetracycline resistance genes and the strA-strB streptomycin resistance genes. Despite Acinetobacter populations being considered natural hosts of LowGC plasmids, these plasmids were not found in three Acinetobacter isolates from the study farm. The isolates harbored tet(Y)-tet(R) genes in identical genetic surroundings as pFK2-7, however, suggesting genetic exchange between Acinetobacter and LowGC plasmids. Abundance of LowGC plasmids and tet(Y) was correlated in manure and soil samples from the farm, indicating that LowGC plasmids may be involved in the spread of tet(Y) in the environment.© FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.


July 7, 2019  |  

Systems biology-guided biodesign of consolidated lignin conversion

Lignin is the second most abundant biopolymer on the earth, yet its utilization for fungible products is complicated by its recalcitrant nature and remains a major challenge for sustainable lignocellulosic biorefineries. In this study, we used a systems biology approach to reveal the carbon utilization pattern and lignin degradation mechanisms in a unique lignin-utilizing Pseudomonas putida strain (A514). The mechanistic study further guided the design of three functional modules to enable a consolidated lignin bioconversion route. First, P. putida A514 mobilized a dye peroxidase-based enzymatic system for lignin depolymerization. This system could be enhanced by overexpressing a secreted multifunctional dye peroxidase to promote a two-fold enhancement of cell growth on insoluble kraft lignin. Second, A514 employed a variety of peripheral and central catabolism pathways to metabolize aromatic compounds, which can be optimized by overexpressing key enzymes. Third, the ß-oxidation of fatty acid was up-regulated, whereas fatty acid synthesis was down-regulated when A514 was grown on lignin and vanillic acid. Therefore, the functional module for polyhydroxyalkanoate (PHA) production was designed to rechannel ß-oxidation products. As a result, PHA content reached 73% per cell dry weight (CDW). Further integrating the three functional modules enhanced the production of PHA from kraft lignin and biorefinery waste. Thus, this study elucidated lignin conversion mechanisms in bacteria with potential industrial implications and laid out the concept for engineering a consolidated lignin conversion route.


July 7, 2019  |  

Clonal dissemination of Pseudomonas aeruginosa sequence type 235 isolates carrying blaIMP-6 and emergence of blaGES-24 and blaIMP-10 on novel genomic islands PAGI-15 and -16 in South Korea.

A total of 431 Pseudomonas aeruginosa clinical isolates were collected from 29 general hospitals in South Korea in 2015. Antimicrobial susceptibility was tested by the disk diffusion method, and MICs of carbapenems were determined by the agar dilution method. Carbapenemase genes were amplified by PCR and sequenced, and the structures of class 1 integrons surrounding the carbapenemase gene cassettes were analyzed by PCR mapping. Multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were performed for strain typing. Whole-genome sequencing was carried out to analyze P. aeruginosa genomic islands (PAGIs) carrying the blaIMP-6, blaIMP-10, and blaGES-24 genes. The rates of carbapenem-nonsusceptible and carbapenemase-producing P. aeruginosa isolates were 34.3% (148/431) and 9.5% (41/431), respectively. IMP-6 was the most prevalent carbapenemase type, followed by VIM-2, IMP-10, and GES-24. All carbapenemase genes were located on class 1 integrons of 6 different types on the chromosome. All isolates harboring carbapenemase genes exhibited genetic relatedness by PFGE (similarity > 80%); moreover, all isolates were identified as sequence type 235 (ST235), with the exception of two ST244 isolates by MLST. The blaIMP-6, blaIMP-10, and blaGES-24 genes were found to be located on two novel PAGIs, designated PAGI-15 and PAGI-16. Our data support the clonal spread of an IMP-6-producing P. aeruginosa ST235 strain, and the emergence of IMP-10 and GES-24 demonstrates the diversification of carbapenemases in P. aeruginosa in Korea. Copyright © 2016, American Society for Microbiology. All Rights Reserved.


July 7, 2019  |  

Complete genome sequence of a psychotrophic Pseudarthrobacter sulfonivorans strain Ar51 (CGMCC 4.7316), a novel crude oil and multi benzene compounds degradation strain.

Pseudarthrobacter sulfonivorans strain Ar51, a psychotrophic bacterium isolated from the Tibet permafrost of China, can degrade crude oil and multi benzene compounds efficiently in low temperature. Here we report the complete genome sequence of this bacterium. The complete genome sequence of Pseudarthrobacter sulfonivorans strain Ar51, consisting of a cycle chromosome with a size of 5.04Mbp and a cycle plasmid with a size of 12.39kbp. The availability of this genome sequence allows us to investigate the genetic basis of crude oil degradation and adaptation to growth in a nutrient-poor permafrost environment. Copyright © 2016 Elsevier B.V. All rights reserved.


July 7, 2019  |  

Microbial metagenomics mock scenario-based sample simulation (M3S3).

Shotgun sequencing in increasingly applied in clinical microbiology for unbiased culture-independent diagnosis. While software solutions for metagenomics proliferate, integration of metagenomics in clinical care, requires method standardisation and validation. Virtual metagenomics samples could underpin validation by substituting real samples and thus we sought to develop a novel solution for simulation of metagenomics samples based on user-defined clinical scenarios.We designed the Microbial Metagenomics Mock Scenario-based Sample Simulation (M3S3) workflow, which allows users to generate virtual samples from raw reads or assemblies. The M3S3 output is a mock sample in FASTQ or FASTA format. M3S3 was tested by generating virtual samples for ten challenging infectious disease scenarios, involving a background matrix ‘spiked’ in silico with pathogens including mixtures. Replicate samples (seven per scenario) were used to represent different compositional ratios. Virtual samples were analysed using Taxonomer and Kraken db.The ten challenge scenarios were successfully applied, generating 80 samples. For all tested scenarios, the virtual samples showed sequence compositions as predicted from the user input. Spiked pathogen sequences were identified with the majority of the replicates and most exhibited acceptable abundance (deviation between expected and observed abundance of spiked pathogens), with slight differences observed between software tools.Despite demonstrated proof-of-concept, integration of clinical metagenomics in routine microbiology remains a substantial challenge. M3S3 is capable of producing virtual samples on-demand, simulating a spectrum of clinical diagnostic scenarios of varying complexity. The M3S3 tool can therefore support the development and validation of standardised metagenomics applications. Copyright © 2017. Published by Elsevier Ltd.


July 7, 2019  |  

Cupriavidus malaysiensis sp. nov., a novel poly(3-hydroxybutyrate-co-4-hydroxybutyrate) accumulating bacterium isolated from the Malaysian environment.

Bacterial classification on the basis of a polyphasic approach was conducted on three poly(3 hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] accumulating bacterial strains that were isolated from samples collected from Malaysian environments; Kulim Lake, Sg. Pinang river and Sg. Manik paddy field. The Gram-negative, rod-shaped, motile, non-sporulating and non-fermenting bacteria were shown to belong to the genus Cupriavidus of the Betaproteobacteria on the basis of their 16S rRNA gene sequence analyses. The sequence similarity value with their near phylogenetic neighbour, Cupriavidus pauculus LMG3413T, was 98.5%. However, the DNA-DNA hybridization values (8-58%) and ribotyping analysis both enabled these strains to be differentiated from related Cupriavidus species with validly published names. The RiboPrint patterns of the three strains also revealed that the strains were genetically related even though they displayed a clonal diversity. The major cellular fatty acids detected in these strains included C15:0 ISO 2OH/C16:1 ?7c, hexadecanoic (16:0) and cis-11-octadecenoic (C18:1 ?7c). Their G+C contents ranged from 68.0  to 68.6 mol%, and their major isoprenoid quinone was Ubiquinone Q-8. Of these three strains, only strain USMAHM13 (= DSM 25816 = KCTC 32390) was discovered to exhibit yellow pigmentation that is characteristic of the carotenoid family. Their assembled genomes also showed that the three strains were not identical in terms of their genome sizes that were 7.82, 7.95 and 8.70 Mb for strains USMAHM13, USMAA1020 and USMAA2-4, respectively, which are slightly larger than that of Cupriavidus necator H16 (7.42 Mb). The average nucleotide identity (ANI) results indicated that the strains were genetically related and the genome pairs belong to the same species. On the basis of the results obtained in this study, the three strains are considered to represent a novel species for which the name Cupriavidus malaysiensis sp. nov. is proposed. The type strain of the species is USMAA1020T (= DSM 19416T = KCTC 32390T).


July 7, 2019  |  

FDA-CDC antimicrobial resistance isolate bank: A publicly-available resource to support research, development and regulatory requirements.

The FDA-CDC Antimicrobial Resistance Isolate Bank was created in July 2015 as a publicly available resource to combat antimicrobial resistance. It is a curated repository of bacterial isolates with an assortment of clinically-important resistance mechanisms that have been phenotypically and genotypically characterized. In the first two years of operation, the Bank offered 14 panels comprising 496 unique isolates and had filled 486 orders from 394 institutions throughout the United States. New panels are being added. Copyright © 2017 American Society for Microbiology.


July 7, 2019  |  

Complete genomic analysis of multidrug-resistance Pseudomonas aeruginosa Guangzhou-Pae617, the host of megaplasmid pBM413.

We previously described the novel qnrVC6 and blaIMP-45carrying megaplasmid pBM413. This study aimed to investigate the complete genome of multidrug-resistance P. aeruginosa Guangzhou-Pae617, a clinical isolate from the sputum of a patient who was suffering from respiratory disease in Guangzhou, China.The genome was sequenced using Illumina Hiseq 2500 and PacBio RS II sequencers and assembled de novo using HGAP. The genome was automatically and manually annotated.The genome of P. aeruginosa Guangzhou-Pae617 is 6,430,493 bp containing 5881 predicted genes with an average G + C content of 66.43%. The genome showed high similarity to two new sequenced P. aeruginosa strains isolated from New York, USA. From the whole genome sequence, we identified a type IV pilin, two large prophages, 15 antibiotic resistant genes, 5 genes involved in the “Infectious diseases” pathways, and 335 virulence factors.The antibiotic resistance and virulence factors in the genome of P. aeruginosa strain Guangzhou-Pae617 were identified by complete genomic analysis. It contributes to further study on antibiotic resistance mechanism and clinical control of P. aeruginosa. Copyright © 2018 Elsevier Ltd. All rights reserved.


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