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https://www.readbyqxmd.com/read/28821711/genetic-cargo-and-bacterial-species-set-the-rate-of-vesicle-mediated-horizontal-gene-transfer
#1
Frances Tran, James Q Boedicker
Most bacteria release extracellular vesicles (EVs). Recent studies have found these vesicles are capable of gene delivery, however the consequences of vesicle-mediated transfer on the patterns and rates of gene flow within microbial communities remains unclear. Previous studies have not determined the impact of both the genetic cargo and the donor and recipient species on the rate of vesicle-mediated gene exchange. This report examines the potential for EVs as a mechanism of gene transfer within heterogeneous microbial populations...
August 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28812563/multicopy-plasmids-potentiate-the-evolution-of-antibiotic-resistance-in-bacteria
#2
Alvaro San Millan, Jose Antonio Escudero, Danna R Gifford, Didier Mazel, R Craig MacLean
Plasmids are thought to play a key role in bacterial evolution by acting as vehicles for horizontal gene transfer, but the role of plasmids as catalysts of gene evolution remains unexplored. We challenged populations of Escherichia coli carrying the blaTEM-1 β-lactamase gene on either the chromosome or a multicopy plasmid (19 copies per cell) with increasing concentrations of ceftazidime. The plasmid accelerated resistance evolution by increasing the rate of appearance of novel TEM-1 mutations, thereby conferring resistance to ceftazidime, and then by amplifying the effect of TEM-1 mutations due to the increased gene dosage...
November 7, 2016: Nature ecology & evolution
https://www.readbyqxmd.com/read/28809850/function-related-replacement-of-bacterial-siderophore-pathways
#3
Hilke Bruns, Max Crüsemann, Anne-Catrin Letzel, Mohammad Alanjary, James O McInerney, Paul R Jensen, Stefan Schulz, Bradley S Moore, Nadine Ziemert
Bacterial genomes are rife with orphan biosynthetic gene clusters (BGCs) associated with secondary metabolism of unrealized natural product molecules. Often up to a tenth of the genome is predicted to code for the biosynthesis of diverse metabolites with mostly unknown structures and functions. This phenomenal diversity of BGCs coupled with their high rates of horizontal transfer raise questions about whether they are really active and beneficial, whether they are neutral and confer no advantage, or whether they are carried in genomes because they are parasitic or addictive...
August 15, 2017: ISME Journal
https://www.readbyqxmd.com/read/28808128/conjugative-plasmid-transfer-in-xylella-fastidiosa-is-dependent-on-tra-and-trb-operon-functions
#4
Lindsey P Burbank, Christopher R Van Horn
The insect-transmitted plant pathogen Xylella fastidiosa is capable of efficient horizontal gene transfer (HGT) and recombination. Natural transformation occurs at high rates in X. fastidiosa, but there also is evidence that certain strains of X. fastidiosa carry native plasmids equipped with transfer and mobilization genes, suggesting conjugation as an additional mechanism of HGT in some instances. Two operons, tra and trb, putatively encoding a conjugative Type IV secretion system are found in some but not all X...
August 14, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28802274/horizontal-dissemination-of-antimicrobial-resistance-determinants-in-multiple-salmonella-serotypes-following-isolation-from-the-environment-of-commercial-swine-operations-after-manure-application
#5
Suchawan Pornsukarom, Siddhartha Thakur
The aim of this study was to characterize the plasmids carrying antimicrobial resistance (AMR) determinants in multiple Salmonella serotypes recovered from the commercial swine farms environment after manure application on land. Manure and soil samples were collected on day0 before and after manure application on six farms in North Carolina and sequential soil samples were recollected on day7, 14, and 21 from the same plots. All environmental samples were processed for Salmonella and their plasmid contents were further characterized...
August 11, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28802203/disentangling-the-origins-of-virophages-and-polintons
#6
REVIEW
Samuel Campbell, Amr Aswad, Aris Katzourakis
Virophages and polintons are part of a complex system that also involves eukaryotes, giant viruses, as well as other viruses and transposable elements. Virophages are cosmopolitan, being found in environments ranging from the Amazon River to Antarctic hypersaline lakes, while polintons are found in many single celled and multicellular eukaryotes. Virophages and polintons have a shared ancestry, but their exact origins are unknown and obscured by antiquity and extensive horizontal gene transfer (HGT). Paleovirology can help disentangle the complicated gene flow between these two, as well as their giant viral and eukaryotic hosts...
August 9, 2017: Current Opinion in Virology
https://www.readbyqxmd.com/read/28802020/investigating-the-diversity-of-effector-genes-in-the-banana-pathogen-fusarium-oxysporum-f-sp-cubense-reveals-evidence-of-horizontal-gene-transfer
#7
Elizabeth Czislowski, Sam Fraser-Smith, Manuel Zander, Wayne T O'Neill, Rachel A Meldrum, Lucy T T Tran-Nguyen, Jacqueline Batley, Elizabeth A B Aitken
It is hypothesised that the virulence of phytopathogenic fungi is mediated through the secretion of small effector proteins that interfere with the defence responses of the host plant. In Fusarium oxysporum, one family of effectors, the secreted in xylem (SIX) genes, have been identified. We sought to characterise the diversity and evolution of the SIX genes in the banana-infecting lineages of F. oxysporum f.sp. cubense (Foc). Whole-genome sequencing data was generated for the 23 genetic lineages of Foc, which were subsequently queried for the 14 known SIX genes (SIX1-SIX14)...
August 12, 2017: Molecular Plant Pathology
https://www.readbyqxmd.com/read/28799681/genomic-and-clinical-evidence-uncovers-the-enterohepatic-species-helicobacter-valdiviensis-as-a-potential-human-intestinal-pathogen
#8
Pablo Fresia, Ronald Jara, Rafael Sierra, Ignacio Ferrés, Gonzalo Greif, Gregorio Iraola, Luis Collado
BACKGROUND: Helicobacter valdiviensis is a recently described enterohepatic species isolated from wild bird's fecal samples. Currently, its pathogenic potential and clinical significance are unknown mainly due to the lack of whole-genome sequences to compare with other helicobacters and the absence of specific screenings to determine its prevalence in humans. MATERIALS AND METHODS: The species type strain (WBE14(T) ) was whole-genome-sequenced, and comparative analyses were carried out including the genomes from other Helicobacter species to determine the exact phylogenetic position of H...
August 11, 2017: Helicobacter
https://www.readbyqxmd.com/read/28799224/genomic-insights-into-the-pathogenicity-and-environmental-adaptability-of-enterococcus-hirae-r17-isolated-from-pork-offered-for-retail-sale
#9
Zixin Peng, Menghan Li, Wei Wang, Hongtao Liu, Séamus Fanning, Yujie Hu, Jianzhong Zhang, Fengqin Li
Genetic information about Enterococcus hirae is limited, a feature that has compromised our understanding of these clinically challenging bacteria. In this study, comparative analysis was performed of E. hirae R17, a daptomycin-resistant strain isolated from pork purchased from a retail market in Beijing, China, and three other enterococcal genomes (Enterococcus faecium DO, Enterococcus faecalis V583, and E. hirae ATCC(™) 9790). Some 1,412 genes were identified that represented the core genome together with an additional 139 genes that were specific to E...
August 10, 2017: MicrobiologyOpen
https://www.readbyqxmd.com/read/28798375/recurrent-horizontal-transfer-of-arsenite-methyltransferase-genes-facilitated-adaptation-of-life-to-arsenic
#10
Song-Can Chen, Guo-Xin Sun, Barry P Rosen, Si-Yu Zhang, Ye Deng, Bo-Kai Zhu, Christopher Rensing, Yong-Guan Zhu
The toxic metalloid arsenic has been environmentally ubiquitous since life first arose nearly four billion years ago and presents a challenge for the survival of all living organisms. Its bioavailability has varied dramatically over the history of life on Earth. As life spread, biogeochemical and climate changes cyclically increased and decreased bioavailable arsenic. To elucidate the history of arsenic adaptation across the tree of life, we reconstructed the phylogeny of the arsM gene that encodes the As(III) S-adenosylmethionine (SAM) methyltransferase...
August 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28796837/whole-genome-sequence-of-two-rathayibacter-toxicus-strains-reveals-a-tunicamycin-biosynthetic-cluster-similar-to-streptomyces-chartreusis
#11
Aaron J Sechler, Matthew A Tancos, David J Schneider, Jonas G King, Christine M Fennessey, Brenda K Schroeder, Timothy D Murray, Douglas G Luster, William L Schneider, Elizabeth E Rogers
Rathayibacter toxicus is a forage grass associated Gram-positive bacterium of major concern to food safety and agriculture. This species is listed by USDA-APHIS as a plant pathogen select agent because it produces a tunicamycin-like toxin that is lethal to livestock and may be vectored by nematode species native to the U.S. The complete genomes of two strains of R. toxicus, including the type strain FH-79, were sequenced and analyzed in comparison with all available, complete R. toxicus genomes. Genome sizes ranged from 2,343,780 to 2,394,755 nucleotides, with 2079 to 2137 predicted open reading frames; all four strains showed remarkable synteny over nearly the entire genome, with only a small transposed region...
2017: PloS One
https://www.readbyqxmd.com/read/28793862/physical-shearing-imparts-biological-activity-to-dna-and-ability-to-transmit-itself-horizontally-across-species-and-kingdom-boundaries
#12
Gorantla Venkata Raghuram, Deepika Gupta, Siddharth Subramaniam, Ashwini Gaikwad, Naveen Kumar Khare, Malcolm Nobre, Naveen Kumar Nair, Indraneel Mittra
BACKGROUND: We have recently reported that cell-free DNA (cfDNA) fragments derived from dying cells that circulate in blood are biologically active molecules and can readily enter into healthy cells to activate DNA damage and apoptotic responses in the recipients. However, DNA is not conventionally known to spontaneously enter into cells or to have any intrinsic biological activity. We hypothesized that cellular entry and acquisition of biological properties are functions of the size of DNA...
August 9, 2017: BMC Molecular Biology
https://www.readbyqxmd.com/read/28790994/insight-into-the-origin-and-evolution-of-the-vibrio-parahaemolyticus-pandemic-strain
#13
REVIEW
Romilio T Espejo, Katherine García, Nicolas Plaza
A strain of Vibrio parahaemolyticus that emerged in 1995 caused the first known pandemic involving this species. This strain comprises clonal autochthonous ocean-dwelling bacteria whose evolution has occurred in the ocean environment. The low sequence diversity in this population enabled the discovery of information on its origin and evolution that has been hidden in bacterial clones that have evolved over a long period. Multilocus sequencing and microarray analysis, together with phylogenetic analysis, of pandemic and pre-pandemic isolates has suggested that the founder clone was an O3:K6 non-pathogenic strain that initially acquired a toxRS/new region and subsequently acquired at least seven novel genomic islands...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28782269/molecular-evolution-of-acetohydroxyacid-synthase-in-bacteria
#14
Yadi Liu, Yanyan Li, Xiaoyuan Wang
Acetohydroxyacid synthase (AHAS) is the key enzyme in the biosynthetic pathways of branched chain amino acids in bacteria. Since it does not exist in animal and plant cells, AHAS is an attractive target for developing antimicrobials and herbicides. In some bacteria, there is a single copy of AHAS, while in others there are multiple copies. Therefore, it is necessary to investigate the origin and evolutionary pathway of various AHASs in bacteria. In this study, all the available protein sequences of AHAS in bacteria were investigated, and an evolutionary model of AHAS in bacteria is proposed, according to gene structure, organization and phylogeny...
August 6, 2017: MicrobiologyOpen
https://www.readbyqxmd.com/read/28780691/mathematical-model-for-the-transport-of-fluoroquinolone-and-its-resistant-bacteria-in-aquatic-environment
#15
Ritu Gothwal, Shashidhar Thatikonda
Development of antibiotic resistance in environmental bacteria is a direct threat to public health. Therefore, it becomes necessary to understand the fate and transport of antibiotic and its resistant bacteria. This paper presents a mathematical model for spatial and temporal transport of fluoroquinolone and its resistant bacteria in the aquatic environment of the river. The model includes state variables for organic matter, fluoroquinolone, heavy metals, and susceptible and resistant bacteria in the water column and sediment bed...
August 5, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28780361/untreated-urban-waste-contaminates-indian-river-sediments-with-resistance-genes-to-last-resort-antibiotics
#16
Nachiket P Marathe, Chandan Pal, Swapnil S Gaikwad, Viktor Jonsson, Erik Kristiansson, D G Joakim Larsson
Efficient sewage treatment is critical for limiting environmental transmission of antibiotic-resistant bacteria. In many low and middle income countries, however, large proportions of sewage are still released untreated into receiving water bodies. In-depth knowledge of how such discharges of untreated urban waste influences the environmental resistome is largely lacking. Here, we highlight the impact of uncontrolled discharge of partially treated and/or untreated wastewater on the structure of bacterial communities and resistome of sediments collected from Mutha river flowing through Pune city in India...
July 25, 2017: Water Research
https://www.readbyqxmd.com/read/28780258/behavior-of-antibiotic-resistance-genes-during-co-composting-of-swine-manure-with-chinese-medicinal-herbal-residues
#17
Li Zhang, Jie Gu, Xiaojuan Wang, Wei Sun, Yanan Yin, Yixin Sun, Aiyun Guo, Xiaxia Tuo
Swine manure is considered to be a reservoir for antibiotic resistance genes (ARGs) but little is known about the variations in ARGs during the co-composting of swine manure with Chinese medicinal herbal residues (CMHRs). Thus, this study explored the effects of CMHRs on the variations in ARGs during co-composting with swine manure. The results showed that CMHRs could reduce effectively most of the targeted ARGs (0.18-2.82logs) and mobile genetic elements (MGEs) (0.47-3.34logs). The correlations indicated that CMHRs might decrease the spread of ARGs via horizontal gene transfer...
July 8, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28769910/plasmid-transfer-in-the-ocean-a-case-study-from-the-roseobacter-group
#18
Jörn Petersen, Irene Wagner-Döbler
Plasmid mediated horizontal gene transfer (HGT) has been speculated to be one of the prime mechanisms for the adaptation of roseobacters (Rhodobacteraceae) to their ecological niches in the marine habitat. Their plasmids contain ecologically crucial functional modules of up to ∼40-kb in size, e.g., for aerobic anoxygenic photosynthesis, flagellar formation and the biosynthesis of the antibiotic tropodithietic acid. Furthermore, the widely present type four secretion system (T4SS) of roseobacters has been shown to mediate conjugation across genus barriers, albeit in the laboratory...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28769116/the-reverse-transcriptases-associated-with-crispr-cas-systems
#19
Nicolás Toro, Francisco Martínez-Abarca, Alejandro González-Delgado
CRISPR (clustered regularly interspaced short palindromic repeats) and associated proteins (Cas) act as adaptive immune systems in bacteria and archaea. Some CRISPR-Cas systems have been found to be associated with putative reverse transcriptases (RT), and an RT-Cas1 fusion associated with a type III-B system has been shown to acquire RNA spacers in vivo. Nevertheless, the origin and evolutionary relationships of these RTs and associated CRISPR-Cas systems remain largely unknown. We performed a comprehensive phylogenetic analysis of these RTs and associated Cas1 proteins, and classified their CRISPR-Cas modules...
August 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28765541/in-silico-analyses-of-conservational-functional-and-phylogenetic-distribution-of-the-luxi-and-luxr-homologs-in-gram-positive-bacteria
#20
Akanksha Rajput, Manoj Kumar
LuxI and LuxR are key factors that drive quorum sensing (QS) in bacteria through secretion and perception of the signaling molecules e.g. N-Acyl homoserine lactones (AHLs). The role of these proteins is well established in Gram-negative bacteria for intercellular communication but remain under-explored in Gram-positive bacteria where QS peptides are majorly responsible for cell-to-cell communication. Therefore, in the present study, we explored conservation, potential function, topological arrangements and evolutionarily aspects of these proteins in Gram-positive bacteria...
August 1, 2017: Scientific Reports
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