scholarly journals Acanthamoeba polyphaga Mimivirus Prevents Amoebal Encystment-Mediating Serine Proteinase Expression and Circumvents Cell Encystment

2014 ◽  
Vol 89 (5) ◽  
pp. 2962-2965 ◽  
Author(s):  
Paulo Boratto ◽  
Jonas Dutra Albarnaz ◽  
Gabriel Magno de Freitas Almeida ◽  
Lucas Botelho ◽  
Alide Caroline Lima Fontes ◽  
...  
Keyword(s):  
Serine Proteinase ◽  
Giant Virus ◽  
Acanthamoeba Polyphaga ◽  
Free Living ◽  
Content Type ◽  
Acanthamoeba Polyphaga Mimivirus

Acanthamoebais a genus of free-living amoebas distributed worldwide. Few studies have explored the interactions between these protozoa and their infecting giant virus,Acanthamoeba polyphagamimivirus (APMV). Here we show that, once the amoebal encystment is triggered, trophozoites become significantly resistant to APMV. Otherwise, upon infection, APMV is able to interfere with the expression of a serine proteinase related to amoebal encystment and the encystment can no longer be triggered.

scholarly journals Mycobacterium gilvum Illustrates Size-Correlated Relationships between Mycobacteria and Acanthamoeba polyphaga

2012 ◽  
Vol 79 (5) ◽  
pp. 1606-1611 ◽  
Author(s):  
Otmane Lamrabet ◽  
Michel Drancourt
Keyword(s):  
Electron Microscopy ◽  
Experimental Study ◽  
Acanthamoeba Polyphaga ◽  
Free Living ◽  
Content Type ◽  
Rapidly Growing Mycobacteria ◽  
Optical And Electron Microscopy ◽  
Negative Controls ◽  
Soil And Water

ABSTRACTMycobacteria are isolated from soil and water environments, where free-living amoebae live. Free-living amoebae are bactericidal, yet some rapidly growing mycobacteria are amoeba-resistant organisms that survive in the amoebal trophozoites and cysts. Such a capacity has not been studied for the environmental rapidly growing organismMycobacterium gilvum. We investigated the ability ofM. gilvumto survive in the trophozoites ofAcanthamoeba polyphagastrain Linc-AP1 by using optical and electron microscopy and culture-based microbial enumerations in the presence of negative controls. We observed that 29% ofA. polyphagacells were infected byM. gilvummycobacteria by 6 h postinfection. SurvivingM. gilvummycobacteria did not multiply and did not kill the amoebal trophozoites during a 5-day coculture. Extensive electron microscopy observations indicated thatM. gilvummeasured 1.4 ± 0.5 μm and failed to findM. gilvumorganisms in the amoebal cysts. Further experimental study of two other rapidly growing mycobacteria,Mycobacterium rhodesiaeandMycobacterium thermoresistibile, indicated that both measured <2 μm and exhibited the same amoeba-mycobacterium relationships asM. gilvum. In general, we observed that mycobacteria measuring <2 μm do not significantly grow within and do not kill amoebal trophozoites, in contrast to mycobacteria measuring >2 μm (P< 0.05). The mechanisms underlying such an observation remain to be determined.

scholarly journals Mimivirus Fibrils Are Important for Viral Attachment to the Microbial World by a Diverse Glycoside Interaction Repertoire

2015 ◽  
Vol 89 (23) ◽  
pp. 11812-11819 ◽  
Author(s):  
Rodrigo Araújo Lima Rodrigues ◽  
Ludmila Karen dos Santos Silva ◽  
Fábio Pio Dornas ◽  
Danilo Bretas de Oliveira ◽  
Thais Furtado Ferreira Magalhães ◽  
...  
Keyword(s):  
Acanthamoeba Castellanii ◽  
Giant Virus ◽  
Microbial World ◽  
Content Type ◽  
Viral Attachment ◽  
Gram Positive Bacteria ◽  
Double Stranded Dna ◽  
Viral Progeny ◽  
Acanthamoeba Polyphaga Mimivirus ◽  
Successful Production

ABSTRACTAcanthamoeba polyphaga mimivirus(APMV) is a giant virus from theMimiviridaefamily. It has many unusual features, such as a pseudoicosahedral capsid that presents a starfish shape in one of its vertices, through which the ∼1.2-Mb double-stranded DNA is released. It also has a dense glycoprotein fibril layer covering the capsid that has not yet been functionally characterized. Here, we verified that although these structures are not essential for viral replication, they are truly necessary for viral adhesion to amoebae, its natural host. In the absence of fibrils, APMV had a significantly lower level of attachment to theAcanthamoeba castellaniisurface. This adhesion is mediated by glycans, specifically, mannose andN-acetylglucosamine (a monomer of chitin and peptidoglycan), both of which are largely distributed in nature as structural components of several organisms. Indeed, APMV was able to attach to different organisms, such as Gram-positive bacteria, fungi, and arthropods, but not to Gram-negative bacteria. This prompted us to predict that (i) arthropods, mainly insects, might act as mimivirus dispersers and (ii) by attaching to other microorganisms, APMV could be ingested by amoebae, leading to the successful production of viral progeny. To date, this mechanism has never been described in the virosphere.IMPORTANCEAPMV is a giant virus that is both genetically and structurally complex. Its size is similar to that of small bacteria, and it replicates inside amoebae. The viral capsid is covered by a dense glycoprotein fibril layer, but its function has remained unknown, until now. We found that the fibrils are not essential for mimivirus replication but that they are truly necessary for viral adhesion to the cell surface. This interaction is mediated by glycans, mainlyN-acetylglucosamine. We also verified that APMV is able to attach to bacteria, fungi, and arthropods. This indicates that insects might act as mimivirus dispersers and that adhesion to other microorganisms could facilitate viral ingestion by amoebae, a mechanism never before described in the virosphere.

Characterization of an aminotransferase from Acanthamoeba polyphaga Mimivirus

2021 ◽  
Author(s):  
Chase A. Seltzner ◽  
Justin D. Ferek ◽  
James B. Thoden ◽  
Hazel M. Holden
Keyword(s):  
Acanthamoeba Polyphaga ◽  
Acanthamoeba Polyphaga Mimivirus

scholarly journals Complete Genome Sequence of the Arcobacter halophilus Type Strain CCUG 53805

2018 ◽  
Vol 7 (14) ◽  
Author(s):  
William G. Miller ◽  
Emma Yee ◽  
James L. Bono
Keyword(s):  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Type Strain ◽  
Marine Environments ◽  
Free Living ◽  
Content Type

Many Arcobacter spp. are free living and are routinely recovered from marine environments.

scholarly journals A Sulfoglycolytic Entner-Doudoroff Pathway in Rhizobium leguminosarum bv. trifolii SRDI565

2020 ◽  
Vol 86 (15) ◽  
Author(s):  
Jinling Li ◽  
Ruwan Epa ◽  
Nichollas E. Scott ◽  
Dominik Skoneczny ◽  
Mahima Sharma ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Glycolytic Enzyme ◽  
Proteomics Data ◽  
Free Living ◽  
Content Type ◽  
Biochemical Processes ◽  
Symbiotic Relationships ◽  
Rhizobium Isolate ◽  
Rhizobial Isolate ◽  
Metabolomics Analysis

ABSTRACT Rhizobia are nitrogen-fixing bacteria that engage in symbiotic relationships with plant hosts but can also persist as free-living bacteria in the soil and rhizosphere. Here, we show that free-living Rhizobium leguminosarum SRDI565 can grow on the sulfosugar sulfoquinovose (SQ) or the related glycoside SQ-glycerol using a sulfoglycolytic Entner-Doudoroff (sulfo-ED) pathway, resulting in production of sulfolactate (SL) as the major metabolic end product. Comparative proteomics supports the involvement of a sulfo-ED operon encoding an ABC transporter, sulfo-ED enzymes, and an SL exporter. Consistent with an oligotrophic lifestyle, proteomics data revealed little change in expression of the sulfo-ED proteins during growth on SQ versus mannitol, a result confirmed through biochemical assay of sulfoquinovosidase activity in cell lysates. Metabolomics analysis showed that growth on SQ involves gluconeogenesis to satisfy metabolic requirements for glucose-6-phosphate and fructose-6-phosphate. Metabolomics analysis also revealed the unexpected production of small amounts of sulfofructose and 2,3-dihydroxypropanesulfonate, which are proposed to arise from promiscuous activities of the glycolytic enzyme phosphoglucose isomerase and a nonspecific aldehyde reductase, respectively. The discovery of a rhizobium isolate with the ability to degrade SQ builds our knowledge of how these important symbiotic bacteria persist within soil. IMPORTANCE Sulfonate sulfur is a major form of organic sulfur in soils but requires biomineralization before it can be utilized by plants. Very little is known about the biochemical processes used to mobilize sulfonate sulfur. We show that a rhizobial isolate from soil, Rhizobium leguminosarum SRDI565, possesses the ability to degrade the abundant phototroph-derived carbohydrate sulfonate SQ through a sulfoglycolytic Entner-Doudoroff pathway. Proteomics and metabolomics demonstrated the utilization of this pathway during growth on SQ and provided evidence for gluconeogenesis. Unexpectedly, off-cycle sulfoglycolytic species were also detected, pointing to the complexity of metabolic processes within cells under conditions of sulfoglycolysis. Thus, rhizobial metabolism of the abundant sulfosugar SQ may contribute to persistence of the bacteria in the soil and to mobilization of sulfur in the pedosphere.

scholarly journals Draft Genome Sequence of Rhizobium tropici SARCC-755, a Free-Living Rhizobium That Nodulated and Promoted Growth in Pigeonpea [Cajanus cajan (L.) Millsp.]

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Francina Lebogang Bopape ◽  
Ahmed Idris Hassen ◽  
Zacharias H. Swanevelder ◽  
Eastonce T. Gwata
Keyword(s):  
Genome Sequence ◽  
Cajanus Cajan ◽  
Draft Genome ◽  
Soil Bacterium ◽  
Draft Genome Sequence ◽  
Rhizobium Tropici ◽  
Free Living ◽  
Content Type ◽  
Legume Plant ◽  
The Common

Rhizobium tropici SARCC-755 is a free-living soil bacterium that formed nodules on pigeonpea roots in the present study. However, the draft genome sequence reveals that this Rhizobium species contains the nolR gene but lacks the common nodulation (nodABC) genes and probably uses other pathways to induce nodules on the legume plant.

scholarly journals Dynamics of Chromosome Replication and Its Relationship to Predatory Attack Lifestyles inBdellovibrio bacteriovorus

2019 ◽  
Vol 85 (14) ◽  
Author(s):  
Łukasz Makowski ◽  
Damian Trojanowski ◽  
Rob Till ◽  
Carey Lambert ◽  
Rebecca Lowry ◽  
...  
Keyword(s):  
Life Cycle ◽  
Subcellular Localization ◽  
Bacterial Infections ◽  
Chromosome Replication ◽  
Free Living ◽  
Gram Negative ◽  
Content Type ◽  
Reproductive Phase ◽  
Attack Phase ◽  
Two Phases

ABSTRACTBdellovibrio bacteriovorusis a small Gram-negative, obligate predatory bacterium that is largely found in wet, aerobic environments (e.g., soil). This bacterium attacks and invades other Gram-negative bacteria, including animal and plant pathogens. The intriguing life cycle ofB. bacteriovorusconsists of two phases: a free-living nonreplicative attack phase, in which the predatory bacterium searches for its prey, and a reproductive phase, in whichB. bacteriovorusdegrades a host’s macromolecules and reuses them for its own growth and chromosome replication. Although the cell biology of this predatory bacterium has gained considerable interest in recent years, we know almost nothing about the dynamics of its chromosome replication. Here, we performed a real-time investigation into the subcellular localization of the replisome(s) in single cells ofB. bacteriovorus. Our results show that inB. bacteriovorus, chromosome replication takes place only during the reproductive phase and exhibits a novel spatiotemporal arrangement of replisomes. The replication process starts at the invasive pole of the predatory bacterium inside the prey cell and proceeds until several copies of the chromosome have been completely synthesized. Chromosome replication is not coincident with the predator cell division, and it terminates shortly before synchronous predator filament septation occurs. In addition, we demonstrate that if thisB. bacteriovoruslife cycle fails in some cells ofEscherichia coli, they can instead use second prey cells to complete their life cycle.IMPORTANCENew strategies are needed to combat multidrug-resistant bacterial infections. Application of the predatory bacteriumBdellovibrio bacteriovorus, which kills other bacteria, including pathogens, is considered promising for combating bacterial infections. TheB. bacteriovoruslife cycle consists of two phases, a free-living, invasive attack phase and an intracellular reproductive phase, in which this predatory bacterium degrades the host’s macromolecules and reuses them for its own growth. To understand the use ofB. bacteriovorusas a “living antibiotic,” it is first necessary to dissect its life cycle, including chromosome replication. Here, we present a real-time investigation into subcellular localization of chromosome replication in a single cell ofB. bacteriovorus. This process initiates at the invasion pole ofB. bacteriovorusand proceeds until several copies of the chromosome have been completely synthesized. Interestingly, we demonstrate that some cells ofB. bacteriovorusrequire two prey cells sequentially to complete their life cycle.

scholarly journals Giant virus vs amoeba: fight for supremacy

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Graziele Oliveira ◽  
Bernard La Scola ◽  
Jônatas Abrahão
Keyword(s):  
Giant Virus ◽  
Host Pathogen Interactions ◽  
Free Living ◽  
Host Interactions ◽  
Virus Particles ◽  
Recent Advances ◽  
Host Pathogen ◽  
New Hosts ◽  
Giant Viruses

Abstract Since the discovery of mimivirus, numerous giant viruses associated with free-living amoebae have been described. The genome of giant viruses can be more than 2.5 megabases, and virus particles can exceed the size of many bacteria. The unexpected characteristics of these viruses have made them intriguing research targets and, as a result, studies focusing on their interactions with their amoeba host have gained increased attention. Studies have shown that giant viruses can establish host–pathogen interactions, which have not been previously demonstrated, including the unprecedented interaction with a new group of small viruses, called virophages, that parasitize their viral factories. In this brief review, we present recent advances in virophage–giant virus–host interactions and highlight selected studies involving interactions between giant viruses and amoebae. These unprecedented interactions involve the giant viruses mimivirus, marseillevirus, tupanviruses and faustovirus, all of which modulate the amoeba environment, affecting both their replication and their spread to new hosts.

scholarly journals Free-Living and Particle-Associated Bacterioplankton in Large Rivers of the Mississippi River Basin Demonstrate Biogeographic Patterns

2014 ◽  
Vol 80 (23) ◽  
pp. 7186-7195 ◽  
Author(s):  
Colin R. Jackson ◽  
Justin J. Millar ◽  
Jason T. Payne ◽  
Clifford A. Ochs
Keyword(s):  
River Basin ◽  
Mississippi River ◽  
River System ◽  
Nutrient Status ◽  
Large Rivers ◽  
Mississippi River Basin ◽  
Free Living ◽  
Content Type ◽  
Biogeographic Patterns ◽  
Bacterioplankton Communities

ABSTRACTThe different drainage basins of large rivers such as the Mississippi River represent interesting systems in which to study patterns in freshwater microbial biogeography. Spatial variability in bacterioplankton communities in six major rivers (the Upper Mississippi, Missouri, Illinois, Ohio, Tennessee, and Arkansas) of the Mississippi River Basin was characterized using Ion Torrent 16S rRNA amplicon sequencing. When all systems were combined, particle-associated (>3 μm) bacterial assemblages were found to be different from free-living bacterioplankton in terms of overall community structure, partly because of differences in the proportional abundance of sequences affiliated with major bacterial lineages (Alphaproteobacteria,Cyanobacteria, andPlanctomycetes). Both particle-associated and free-living communities ordinated by river system, a pattern that was apparent even after rare sequences or those affiliated withCyanobacteriawere removed from the analyses. Ordination of samples by river system correlated with environmental characteristics of each river, such as nutrient status and turbidity. Communities in the Upper Mississippi and the Missouri and in the Ohio and the Tennessee, pairs of rivers that join each other, contained similar taxa in terms of presence-absence data but differed in the proportional abundance of major lineages. The most common sequence types detected in particle-associated communities were picocyanobacteria in theSynechococcus/Prochlorococcus/Cyanobium(Syn/Pro) clade, while free-living communities also contained a high proportion of LD12 (SAR11/Pelagibacter)-likeAlphaproteobacteria. This research shows that while different tributaries of large river systems such as the Mississippi River harbor distinct bacterioplankton communities, there is also microhabitat variation such as that between free-living and particle-associated assemblages.

scholarly journals Behavior of Yersinia enterocolitica in the Presence of the Bacterivorous Acanthamoeba castellanii

2013 ◽  
Vol 79 (20) ◽  
pp. 6407-6413 ◽  
Author(s):  
E. Lambrecht ◽  
J. Baré ◽  
I. Van Damme ◽  
W. Bert ◽  
K. Sabbe ◽  
...  
Keyword(s):  
Yersinia Enterocolitica ◽  
Pathogenic Bacteria ◽  
Acanthamoeba Castellanii ◽  
Ecological Niches ◽  
Free Living ◽  
Content Type ◽  
Food Borne ◽  
Transmission Electron ◽  
Set Up ◽  
The Impact

ABSTRACTFree-living protozoa play an important role in the ecology and epidemiology of human-pathogenic bacteria. In the present study, the interaction betweenYersinia enterocolitica, an important food-borne pathogen, and the free-living amoebaAcanthamoeba castellaniiwas studied. Several cocultivation assays were set up to assess the resistance ofY. enterocoliticatoA. castellaniipredation and the impact of environmental factors and bacterial strain-specific characteristics. Results showed that allY. enterocoliticastrains persist in association withA. castellaniifor at least 14 days, and associations withA. castellaniienhanced survival ofYersiniaunder nutrient-rich conditions at 25°C and under nutrient-poor conditions at 37°C. Amoebae cultivated in the supernatant of oneYersiniastrain showed temperature- and time-dependent permeabilization. Intraprotozoan survival ofY. enterocoliticadepended on nutrient availability and temperature, with up to 2.8 log CFU/ml bacteria displaying intracellular survival at 7°C for at least 4 days in nutrient-rich medium. Transmission electron microscopy was performed to locate theYersiniacells inside the amoebae. AsYersiniaandAcanthamoebashare similar ecological niches, this interaction identifies a role of free-living protozoa in the ecology and epidemiology ofY. enterocolitica.

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