Dietary intake of L-carnitine can promote cardiovascular diseases in humans through microbial production of trimethylamine (TMA) and its subsequent oxidation to trimethylamine N-oxide by hepatic ...flavin-containing monooxygenases. Although our microbiota are responsible for TMA formation from carnitine, the underpinning molecular and biochemical mechanisms remain unclear. In this study, using bioinformatics approaches, we first identified a two-component Rieske-type oxygenase/reductase (CntAB) and associated gene cluster proposed to be involved in carnitine metabolism in representative genomes of the human microbiota. CntA belongs to a group of previously uncharacterized Rieske-type proteins and has an unusual "bridging" glutamate but not the aspartate residue, which is believed to facilitate intersubunit electron transfer between the Rieske center and the catalytic mononuclear iron center. Using Acinetobacter baumannii as the model, we then demonstrate that cntAB is essential in carnitine degradation to TMA. Heterologous overexpression of cntAB enables Escherichia coli to produce TMA, confirming that these genes are sufficient in TMA formation. Site-directed mutagenesis experiments have confirmed that this unusual "bridging glutamate" residue in CntA is essential in catalysis and neither mutant (E205D, E205A) is able to produce TMA. Taken together, the data in our study reveal the molecular and biochemical mechanisms underpinning carnitine metabolism to TMA in human microbiota and assign the role of this novel group of Rieske-type proteins in microbial carnitine metabolism.
The investigation of the microbial populations of the human body, known as the microbiome, has led to a revolutionary field of science, and understanding of its impacts on human development and ...health. The majority of microbiome research to date has focussed on bacteria and other kingdoms of life, such as fungi. Trailing behind these is the interrogation of the gut viruses, specifically the phageome. Bacteriophages, viruses that infect bacterial hosts, are known to dictate the dynamics and diversity of bacterial populations in a number of ecosystems. However, the phageome of the human gut, while of apparent importance, remains an area of many unknowns. In this paper we discuss the role of bacteriophages within the human gut microbiome. We examine the methods used to study bacteriophage populations, how this evolved over time and what we now understand about the phageome. We review the phageome development in infancy, and factors that may influence phage populations in adult life. The role and action of the phageome is then discussed at both a biological-level, and in the broader context of human health and disease.
Soil viruses can moderate the roles that their host microbes play in global carbon cycling. However, given that most studies investigate the surface layer (i.e., top 20 cm) of soil, the extent to ...which this occurs in subsurface soil (i.e., below 20 cm) is unknown. Here, we leveraged public sequencing data to investigate the interactions between viruses and their hosts at soil depth intervals, down to 115 cm. While most viruses were detected throughout the soil depth profile, their adaptation to host microbes varied. Nonetheless, we uncovered evidence for the potential of soil viruses to encourage their hosts to recycle plant-derived carbon in both surface and subsurface soils. This work reasons that our understanding of soil viral functions requires us to continue to dig deeper and compare viruses existing throughout soil ecosystems.
Klebsiella infections, including catheter associated urinary tract infections, are a considerable burden on health care systems. This is due to their difficulty to treat, caused by antimicrobial ...resistance and their ability to form biofilms. In this study, we investigated the use of a Klebsiella phage cocktail to reduce biofilm viability. We used two methodologies to investigate this, a standard 96-well plate assay and a more complicated Foley catheter-based model. The phage cocktail was used alone and in combination with clinically relevant antibiotic treatments. Viability was measured by both a resazurin based stain and colony forming unit counts, of cells sloughed off from the biofilm. We showed that phage infection dynamics and host survival vary significantly in different standard laboratory media, presumably due to the expression of different surface receptors and capsule composition by the bacteria effecting phage binding. This underscores the importance of a realistic model for developing phage therapy.
We demonstrate that bacteriophage-based treatments are a viable option for preventing Klebsiella colonisation and biofilm formation on urinary catheters. Phage cocktails were able to significantly reduce the amount of biofilm that formed when they were present during early biofilm formation. The phages used in this study were unable to significantly reduce a pre-formed mature biofilm, despite encoding depolymerases. Phages applied together with antimicrobial treatments, showed synergistic interactions, in some cases the combined treatment was much more effective than antimicrobial treatments alone.
We show that phage cocktails have the potential to prevent Klebsiella biofilms in catheters, if used early or as a preventative treatment and will work well alongside standard antibiotics in the treatment of catheter-associated urinary tract infections (CAUTI).
The rumen contains a multi-kingdom, commensal microbiome, including protozoa, bacteria, archaea, fungi and viruses, which enables ruminant herbivores to ferment and utilize plant feedstuffs that ...would be otherwise indigestible. Within the rumen, virus populations are diverse and highly abundant, often out-numbering the microbial populations that they both predate on and co-exist with. To date the research effort devoted to understanding rumen-associated viral populations has been considerably less than that given to the other microbial populations, yet their contribution to maintaining microbial population balance, intra-ruminal microbial lysis, fiber breakdown, nutrient cycling and genetic transfer may be highly significant. This review follows the technological advances which have contributed to our current understanding of rumen viruses and drawing on knowledge from other environmental and animal-associated microbiomes, describes the known and potential roles and impacts viruses have on rumen function and speculates on the future directions of rumen viral research.
is a clinically relevant opportunistic pathogen belonging to the
family. It is in the top three bacteria associated with antimicrobial resistance deaths globally, and one of the most dangerous ...bacteria causing nosocomial infections. Phage therapy offers a potential option for the treatment of drug-resistant bacterial infections.
Phage PSKP16 was isolated against
, capsular type K2 (isolated from a wound infection). PSKP16 is a new lytic phage with a
-like morphology.
PSKP16 is a linear double stranded DNA phage with a GC content of 50% and genome size of 46,712 bp, for which we predicted 67 ORFs. PSKP16 belongs to the genus
and shows high evolutionary proximity to
phages JY917, Sushi, and B1.
Phage isolation is fast, cheap and efficient, but it requires time and characterization (which adds expense) to ensure that the isolated phages do not pose a health risk, which is essential to safely use phage therapy to treat life-threatening bacterial infections.
The rhizosphere is a hotspot for microbial activity and contributes to ecosystem services including plant health and biogeochemical cycling. The activity of microbial viruses, and their influence on ...plant-microbe interactions in the rhizosphere, remains undetermined. Given the impact of viruses on the ecology and evolution of their host communities, determining how soil viruses influence microbiome dynamics is crucial to build a holistic understanding of rhizosphere functions.
Here, we aimed to investigate the influence of crop management on the composition and activity of bulk soil, rhizosphere soil, and root viral communities. We combined viromics, metagenomics, and metatranscriptomics on soil samples collected from a 3-year crop rotation field trial of oilseed rape (Brassica napus L.). By recovering 1059 dsDNA viral populations and 16,541 ssRNA bacteriophage populations, we expanded the number of underexplored Leviviricetes genomes by > 5 times. Through detection of viral activity in metatranscriptomes, we uncovered evidence of "Kill-the-Winner" dynamics, implicating soil bacteriophages in driving bacterial community succession. Moreover, we found the activity of viruses increased with proximity to crop roots, and identified that soil viruses may influence plant-microbe interactions through the reprogramming of bacterial host metabolism. We have provided the first evidence of crop rotation-driven impacts on soil microbial communities extending to viruses. To this aim, we present the novel principal of "viral priming," which describes how the consecutive growth of the same crop species primes viral activity in the rhizosphere through local adaptation.
Overall, we reveal unprecedented spatial and temporal diversity in viral community composition and activity across root, rhizosphere soil, and bulk soil compartments. Our work demonstrates that the roles of soil viruses need greater consideration to exploit the rhizosphere microbiome for food security, food safety, and environmental sustainability. Video Abstract.
Electronic gaming as pain distraction Jameson, Eleanor; Trevena, Judy; Swain, Nic
Pain research & management,
2011 Jan-Feb, 2011-01-00, 20110101, 2011-01-01, Letnik:
16, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The current study investigated whether active distraction reduces participants' experience of pain more than passive distraction during a cold pressor task. In the first experiment, 60 participants ...were asked to submerge their hand in cold (2°C) water for as long as they could tolerate. They did this with no distraction, and then with active (electronic gaming system) and passive (television) distraction, in randomly assigned order. Tolerance time, pain intensity ratings and task absorption ratings were measured for each condition. A second experiment attempted to control for participants' expectations about the effects of distraction on pain. Forty participants underwent the same experimental procedure, but were given verbal suggestions about the effects of distraction by the experimenter before each distraction condition. Participants in both experiments had a significantly higher pain tolerance and reported less pain with the active distraction compared with passive or no distraction. Participants reported being more absorbed, and were significantly more willing to do the task again when they had the active distraction compared with both passive distraction and no distraction. They also had more enjoyment, less anxiety and greater reduction in pain with active distraction than with passive distraction. There was no effect of suggestion. These experiments offer further support for the use of electronic games as a method of pain control.
Coastal environments are dynamic and rapidly changing. Living organisms in coastal environments are known to synthesise large quantities of organic osmolytes, which they use to cope with osmotic ...stresses. The organic osmolyte glycine betaine (GBT) is ubiquitously found in marine biota from prokaryotic Bacteria and Archaea to coastal plants, marine protozoa, and mammals. In intertidal coastal sediment, GBT represents an important precursor of natural methane emissions and as much as 90% of total methane production in these ecosystems can be originated from methanogenesis from GBT and its intermediate trimethylamine through microbial metabolism.
We set out to uncover the microorganisms responsible for methanogenesis from GBT using stable isotope labelling and metagenomics. This led to the recovery of a near-complete genome (2.3 Mbp) of a novel clostridial bacterium involved in anaerobic GBT degradation. Phylogenetic analyses of 16S rRNA gene, functional marker genes, and comparative genomics analyses all support the establishment of a novel family Candidatus 'Betainaceae' fam. nov. in Clostridiales and its role in GBT metabolism.
Our comparative genomes and metagenomics analyses suggest that this bacterium is widely distributed in coastal salt marshes, marine sediments, and deep subsurface sediments, suggesting a key role of anaerobic GBT metabolism by this clostridial bacterium in these ecosystems.
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