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Elizabeth R Sockett - One of the best experts on this subject based on the ideXlab platform.
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microbe profile Bdellovibrio bacteriovorus a specialized bacterial predator of bacteria
Microbiology, 2021Co-Authors: Andrew L Lovering, Elizabeth R SockettAbstract:Bdellovibrio bacteriovorus is an environmentally-ubiquitous bacterium that uses unique adaptations to kill other bacteria. The best-characterized strain, HD100, has a multistage lifestyle, with both a free-living attack phase and an intraperiplasmic growth and division phase inside the prey cell. Advances in understanding the basic biology and regulation of predation processes are paving the way for future potential therapeutic and bioremediation applications of this unusual bacterium.
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engulfment persistence and fate of Bdellovibrio bacteriovorus predators inside human phagocytic cells informs their future therapeutic potential
Scientific Reports, 2019Co-Authors: Dhaarini Raghunathan, Rob Till, David Negus, Christopher I Moore, Paul M Radford, Christopher Gell, Patrick J Tighe, Sally P Wheatley, Luisa Martinezpomares, Elizabeth R SockettAbstract:In assessing the potential of predatory bacteria, such as Bdellovibrio bacteriovorus, to become live therapeutic agents against bacterial infections, it is crucial to understand and quantify Bdellovibrio host cell interactions at a molecular level. Here, we quantify the interactions of live B. bacteriovorus with human phagocytic cells, determining the uptake mechanisms, persistence, associated cytokine responses and intracellular trafficking of the non-growing B. bacteriovorus in PMA-differentiated U937 cells. B. bacteriovorus are engulfed by U937 cells and persist for 24 h without affecting host cell viability and can be observed microscopically and recovered and cultured post-uptake. The uptake of predators is passive and depends on the dynamics of the host cell cytoskeleton; the engulfed predators are eventually trafficked through the phagolysosomal pathway of degradation. We have also studied the prevalence of B. bacteriovorus specific antibodies in the general human population. Together, these results quantify a period of viable persistence and the ultimate fate of B. bacteriovorus inside phagocytic cells. They provide new knowledge on predator availability inside hosts, plus potential longevity and therefore potential efficacy as a treatment in humans and open up future fields of work testing if predators can prey on host-engulfed pathogenic bacteria.
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injections of predatory bacteria work alongside host immune cells to treat shigella infection in zebrafish larvae
Current Biology, 2016Co-Authors: Alexandra R Willis, Carey Lambert, Robert Till, Christopher Moore, Maria Mazonmoya, Sina Krokowski, Serge Mostowy, Elizabeth R SockettAbstract:Bdellovibrio bacteriovorus are predatory bacteria that invade and kill a range of Gram-negative bacterial pathogens in natural environments and in vitro [ 1 and 2]. In this study, we investigated Bdellovibrio as an injected, antibacterial treatment in vivo, using zebrafish (Danio rerio) larvae infected with an antibiotic-resistant strain of the human pathogen Shigella flexneri. When injected alone, Bdellovibrio can persist for more than 24 hr in vivo yet exert no pathogenic effects on zebrafish larvae. Bdellovibrio injection of zebrafish containing a lethal dose of Shigella promotes pathogen killing, leading to increased zebrafish survival. Live-cell imaging of infected zebrafish reveals that Shigella undergo rounding induced by the invasive predation from Bdellovibrio in vivo. Furthermore, Shigella-dependent replication of Bdellovibrio was captured inside the zebrafish larvae, indicating active predation in vivo. Bdellovibrio can be engulfed and ultimately eliminated by host neutrophils and macrophages, yet have a sufficient dwell time to prey on pathogens. Experiments in immune-compromised zebrafish reveal that maximal therapeutic benefits of Bdellovibrio result from the synergy of both bacterial predation and host immunity, but that in vivo predation contributes significantly to the survival outcome. Our results demonstrate that successful antibacterial therapy can be achieved via the host immune system working together with bacterial predation by Bdellovibrio. Such cooperation may be important to consider in the fight against antibiotic-resistant infections in vivo.
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ras gtpase like protein mgla a controller of bacterial social motility in myxobacteria has evolved to control bacterial predation by Bdellovibrio
PLOS Genetics, 2014Co-Authors: David S Milner, Andrew L Lovering, Ian T Cadby, Rob Till, Sarah M Basford, Susan Liddell, Laura E Williams, Emma B Saxon, Elizabeth R SockettAbstract:Bdellovibrio bacteriovorus invade Gram-negative bacteria in a predatory process requiring Type IV pili (T4P) at a single invasive pole, and also glide on surfaces to locate prey. Ras-like G-protein MglA, working with MglB and RomR in the deltaproteobacterium Myxococcus xanthus, regulates adventurous gliding and T4P-mediated social motility at both M. xanthus cell poles. Our bioinformatic analyses suggested that the GTPase activating protein (GAP)-encoding gene mglB was lost in Bdellovibrio, but critical residues for MglABd GTP-binding are conserved. Deletion of mglABd abolished prey-invasion, but not gliding, and reduced T4P formation. MglABd interacted with a previously uncharacterised tetratricopeptide repeat (TPR) domain protein Bd2492, which we show localises at the single invasive pole and is required for predation. Bd2492 and RomR also interacted with cyclic-di-GMP-binding receptor CdgA, required for rapid prey-invasion. Bd2492, RomRBd and CdgA localize to the invasive pole and may facilitate MglA-docking. Bd2492 was encoded from an operon encoding a TamAB-like secretion system. The TamA protein and RomR were found, by gene deletion tests, to be essential for viability in both predatory and non-predatory modes. Control proteins, which regulate bipolar T4P-mediated social motility in swarming groups of deltaproteobacteria, have adapted in evolution to regulate the anti-social process of unipolar prey-invasion in the “lone-hunter” Bdellovibrio. Thus GTP-binding proteins and cyclic-di-GMP inputs combine at a regulatory hub, turning on prey-invasion and allowing invasion and killing of bacterial pathogens and consequent predatory growth of Bdellovibrio.
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nucleases in Bdellovibrio bacteriovorus contribute towards efficient self biofilm formation and eradication of preformed prey biofilms
Fems Microbiology Letters, 2013Co-Authors: Carey Lambert, Elizabeth R SockettAbstract:Bdellovibrio bacteriovorus are predatory bacteria that burrow into prey bacteria and degrade their cell contents, including DNA and RNA, to grow. Their genome encodes diverse nucleases, some with potential export sequences. Transcriptomic analysis determined two candidate-predicted nuclease genes (bd1244, bd1934) upregulated upon contact with prey, which we hypothesised, may be involved in prey nucleic acid degradation. RT-PCR on total RNA from across the predatory cycle confirmed that the transcription of these genes peaks shortly after prey cell invasion, around the time that prey DNA is being degraded. We deleted bd1244 and bd1934 both singly and together and investigated their role in predation of prey cells and biofilms. Surprisingly, we found that the nuclease-mutant strains could still prey upon planktonic bacteria as efficiently as wild type and still degraded the prey genomic DNA. The Bdellovibrio nuclease mutants were less efficient at (self-) biofilm formation, and surprisingly, they showed enhanced predatory clearance of preformed prey cell biofilms relative to wild-type Bdellovibrio.
Carey Lambert - One of the best experts on this subject based on the ideXlab platform.
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fluorescent d amino acids reveal bi cellular cell wall modifications important for Bdellovibrio bacteriovorus predation
Nature microbiology, 2017Co-Authors: Carey Lambert, Rob Till, Erkin Kuru, Jonathan Rittichier, Adrien Ducret, Adeline Derouaux, Joe W GrayAbstract:Modification of essential bacterial peptidoglycan (PG) containing cell walls can lead to antibiotic resistance, for example β-lactam resistance by L,D-transpeptidase activities. Predatory Bdellovibrio bacteriovorus are naturally antibacterial and combat infections by traversing, modifying and finally destroying walls of Gram-negative prey bacteria, modifying their own PG as they grow inside prey. Historically, these multi-enzymatic processes on two similar PG walls have proved challenging to elucidate. Here, with a PG labelling approach utilizing timed pulses of multiple fluorescent D-amino acids (FDAAs), we illuminate dynamic changes that predator and prey walls go through during the different phases of bacteria:bacteria invasion. We show formation of a reinforced circular port-hole in the prey wall; L,D-transpeptidaseBd mediated D-amino acid modifications strengthening prey PG during Bdellovibrio invasion and a zonal mode of predator-elongation. This process is followed by unconventional, multi-point and synchronous septation of the intracellular Bdellovibrio, accommodating odd- and even-numbered progeny formation by non-binary division.
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injections of predatory bacteria work alongside host immune cells to treat shigella infection in zebrafish larvae
Current Biology, 2016Co-Authors: Alexandra R Willis, Carey Lambert, Robert Till, Christopher Moore, Maria Mazonmoya, Sina Krokowski, Serge Mostowy, Elizabeth R SockettAbstract:Bdellovibrio bacteriovorus are predatory bacteria that invade and kill a range of Gram-negative bacterial pathogens in natural environments and in vitro [ 1 and 2]. In this study, we investigated Bdellovibrio as an injected, antibacterial treatment in vivo, using zebrafish (Danio rerio) larvae infected with an antibiotic-resistant strain of the human pathogen Shigella flexneri. When injected alone, Bdellovibrio can persist for more than 24 hr in vivo yet exert no pathogenic effects on zebrafish larvae. Bdellovibrio injection of zebrafish containing a lethal dose of Shigella promotes pathogen killing, leading to increased zebrafish survival. Live-cell imaging of infected zebrafish reveals that Shigella undergo rounding induced by the invasive predation from Bdellovibrio in vivo. Furthermore, Shigella-dependent replication of Bdellovibrio was captured inside the zebrafish larvae, indicating active predation in vivo. Bdellovibrio can be engulfed and ultimately eliminated by host neutrophils and macrophages, yet have a sufficient dwell time to prey on pathogens. Experiments in immune-compromised zebrafish reveal that maximal therapeutic benefits of Bdellovibrio result from the synergy of both bacterial predation and host immunity, but that in vivo predation contributes significantly to the survival outcome. Our results demonstrate that successful antibacterial therapy can be achieved via the host immune system working together with bacterial predation by Bdellovibrio. Such cooperation may be important to consider in the fight against antibiotic-resistant infections in vivo.
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interrupting peptidoglycan deacetylation during Bdellovibrio predator prey interaction prevents ultimate destruction of prey wall liberating bacterial ghosts
Scientific Reports, 2016Co-Authors: Carey Lambert, Nhat Khai Bui, Thomas R Lerner, Waldemar Vollmer, Shinichi Aizawa, Susan Liddell, Hannah Somers, Ana Clark, Andrew L LoveringAbstract:The peptidoglycan wall, located in the periplasm between the inner and outer membranes of the cell envelope in Gram-negative bacteria, maintains cell shape and endows osmotic robustness. Predatory Bdellovibrio bacteria invade the periplasm of other bacterial prey cells, usually crossing the peptidoglycan layer, forming transient structures called bdelloplasts within which the predators replicate. Prey peptidoglycan remains intact for several hours, but is modified and then degraded by escaping predators. Here we show predation is altered by deleting two Bdellovibrio N-acetylglucosamine (GlcNAc) deacetylases, one of which we show to have a unique two domain structure with a novel regulatory”plug”. Deleting the deacetylases limits peptidoglycan degradation and rounded prey cell “ghosts” persist after mutant-predator exit. Mutant predators can replicate unusually in the periplasmic region between the peptidoglycan wall and the outer membrane rather than between wall and inner-membrane, yet still obtain nutrients from the prey cytoplasm. Deleting two further genes encoding DacB/PBP4 family proteins, known to decrosslink and round prey peptidoglycan, results in a quadruple mutant Bdellovibrio which leaves prey-shaped ghosts upon predation. The resultant bacterial ghosts contain cytoplasmic membrane within bacteria-shaped peptidoglycan surrounded by outer membrane material which could have promise as “bacterial skeletons” for housing artificial chromosomes.
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ankyrin mediated self protection during cell invasion by the bacterial predator Bdellovibrio bacteriovorus
Nature Communications, 2015Co-Authors: Carey Lambert, Ian T Cadby, Rob Till, Nhat Khai Bui, Thomas R Lerner, William S Hughes, David J Lee, Luke J Alderwick, Waldemar VollmerAbstract:Predatory Bdellovibrio bacteriovorus are natural antimicrobial organisms, killing other bacteria by whole-cell invasion. Self-protection against prey-metabolizing enzymes is important for the evolution of predation. Initial prey entry involves the predator's peptidoglycan DD-endopeptidases, which decrosslink cell walls and prevent wasteful entry by a second predator. Here we identify and characterize a self-protection protein from B. bacteriovorus, Bd3460, which displays an ankyrin-based fold common to intracellular pathogens of eukaryotes. Co-crystal structures reveal Bd3460 complexation of dual targets, binding a conserved epitope of each of the Bd3459 and Bd0816 endopeptidases. Complexation inhibits endopeptidase activity and cell wall decrosslinking in vitro. Self-protection is vital - ΔBd3460 Bdellovibrio deleteriously decrosslink self-peptidoglycan upon invasion, adopt a round morphology, and lose predatory capacity and cellular integrity. Our analysis provides the first mechanistic examination of self-protection in Bdellovibrio, documents protection-multiplicity for products of two different genomic loci, and reveals an important evolutionary adaptation to an invasive predatory bacterial lifestyle.
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activity of Bdellovibrio hit locus proteins bd0108 and bd0109 links type iva pilus extrusion retraction status to prey independent growth signalling
PLOS ONE, 2013Co-Authors: Michael J Capeness, Carey Lambert, Andrew L Lovering, Rob Till, David J Lee, Luke J Alderwick, Kaoru Uchida, Roy R Chaudhuri, David Swarbreck, Susan LiddellAbstract:Bdellovibrio bacteriovorus are facultatively predatory bacteria that grow within gram-negative prey, using pili to invade their periplasmic niche. They also grow prey-independently on organic nutrients after undergoing a reversible switch. The nature of the growth switching mechanism has been elusive, but several independent reports suggested mutations in the hit (host-interaction) locus on the Bdellovibrio genome were associated with the transition to prey-independent growth. Pili are essential for prey entry by Bdellovibrio and sequence analysis of the hit locus predicted that it was part of a cluster of Type IVb pilus-associated genes, containing bd0108 and bd0109. In this study we have deleted the whole bd0108 gene, which is unique to Bdellovibrio, and compared its phenotype to strains containing spontaneous mutations in bd0108 and the common natural 42 bp deletion variant of bd0108. We find that deletion of the whole bd0108 gene greatly reduced the extrusion of pili, whereas the 42 bp deletion caused greater pilus extrusion than wild-type. The pili isolated from these strains were comprised of the Type IVa pilin protein; PilA. Attempts to similarly delete gene bd0109, which like bd0108 encodes a periplasmic/secreted protein, were not successful, suggesting that it is likely to be essential for Bdellovibrio viability in any growth mode. Bd0109 has a sugar binding YD- repeat motif and an N-terminus with a putative pilin-like fold and was found to interact directly with Bd0108. These results lead us to propose that the Bd0109/Bd0108 interaction regulates pilus production in Bdellovibrio (possibly by interaction with the pilus fibre at the cell wall), and that the presence (and possibly retraction state) of the pilus feeds back to alter the growth state of the Bdellovibrio cell. We further identify a novel small RNA encoded by the hit locus, the transcription of which is altered in different bd0108 mutation backgrounds.
Edouard Jurkevitch - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of differentially regulated type ivb pilin genes necessary for predation in obligate bacterial predators
Scientific Reports, 2017Co-Authors: Ofir Avidan, Shmuel Pietrokovski, Margarita Petrenko, Rene Becker, Sebastian Beck, Michael W Linscheid, Edouard JurkevitchAbstract:Bdellovibrio bacteriovorus is an obligate predator of bacteria that grows and divides within the periplasm of its prey. Functions involved in the early steps of predation have been identified and characterized, but mediators of prey invasion are still poorly detailed. By combining omics data available for Bdellovibrio and like organisms (BALO’s), we identified 43 genes expressed in B. bacteriovorus during the early interaction with prey. These included genes in a tight adherence (TAD) operon encoding for two type IVb fimbriae-like pilin proteins (flp1 and flp2), and their processing and export machinery. Two additional flp genes (flp3 and flp4) were computationally identified at other locations along the chromosome, defining the largest and most diverse type IVb complement known in bacteria to date. Only flp1, flp2 and flp4 were expressed; their respective gene knock-outs resulted in a complete loss of the predatory ability without losing the ability to adhere to prey cells. Additionally, we further demonstrate differential regulation of the flp genes as the TAD operon of BALOs with different predatory strategies is controlled by a flagellar sigma factor FliA, while flp4 is not. Finally, we show that FliA, a known flagellar transcriptional regulator in other bacteria, is an essential Bdellovibrio gene.
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1 Bdellovibrio and like organisms
2014Co-Authors: Or Rotem, Zohar Pasternak, Edouard JurkevitchAbstract:Bdellovibrio and like organisms (BALOs) are gram-negative, obligate predators of other gram-negative bacteria. These small bacteria interact with their prey as highly motile attack phase cells, attaching to the outer membrane and consuming the prey extracellularly (epibiotic predation) or penetrating their periplasm (periplasmic predation). The former divides in a binary fashion, while the latter grows as a polynucleotide filament to finally split as progeny attack cells. High-resolution microscopy, molecular genetics, genomics, and functional genomics have been applied to study the cell cycle of BALOs, revealing functions required for predation and for cellular organization. Until recently, Bdellovibrio bacteriovorus was the only recognized species of BALOs. Culture-dependent and culture-independent approaches have shown that these predators form diverse monophyletic groups, including the three families Bdellovibrionaceae, Bacteriovoraceae, and Peridibacteraceae in the d-proteobacteria, and the genus Micavibrio in the a-proteobacteria. Based on this detailed taxonomical knowledge, it has become possible to track predator and prey interactions in natural systems, providing first evaluations of the impact of bacterial predation on community structure.
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a global transcriptional switch between the attack and growth forms of Bdellovibrio bacteriovorus
PLOS ONE, 2013Co-Authors: Iris Karunker, Edouard Jurkevitch, Or Rotem, Mally Doribachash, Rotem SorekAbstract:Bdellovibrio bacteriovorus is an obligate predator of bacteria ubiquitously found in the environment. Its life cycle is composed of two essential phases: a free-living, non-replicative, fast swimming attack phase (AP) wherein the predator searches for prey; and a non-motile, actively dividing growth phase (GP) in which it consumes the prey. The molecular regulatory mechanisms governing the switch between AP and GP are largely unknown. We used RNA-seq to generate a single-base-resolution map of the Bdellovibrio transcriptome in AP and GP, revealing a specific "AP" transcriptional program, which is largely mutually exclusive of the GP program. Based on the expression map, most genes in the Bdellovibrio genome are classified as "AP only" or "GP only". We experimentally generated a genome-wide map of 140 AP promoters, controlling the majority of AP-specific genes. This revealed a common sigma-like DNA binding site highly similar to the E. coli flagellar genes regulator sigma28 (FliA). Further analyses suggest that FliA has evolved to become a global AP regulator in Bdellovibrio. Our results also reveal a non-coding RNA that is massively expressed in AP. This ncRNA contains a c-di-GMP riboswitch. We suggest it functions as an intracellular reservoir for c-di-GMP, playing a role in the rapid switch from AP to GP.
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reward for Bdellovibrio bacteriovorus for preying on a polyhydroxyalkanoate producer
Environmental Microbiology, 2013Co-Authors: Virginia Martinez, Jose Luis Garcia, Edouard Jurkevitch, Maria Auxiliadora PrietoAbstract:Summary Bdellovibrio bacteriovorus HD100 is an obligate predator that invades and grows within the peri- plasm of Gram-negative bacteria, including mcl- polyhydroxyalkanoate (PHA) producers such as Pseudomonas putida. We investigated the impact of prey PHA content on the predator fitness and the potential advantages for preying on a PHA producer. Using a new procedure to control P. putida KT2442 cell size we demonstrated that the number of Bdello- vibrio progeny depends on the prey biomass and not on the viable prey cell number or PHA content. The presence of mcl-PHA hydrolysed products in the culture supernatant after predation on P. putida KT42Z, a PHA producing strain lacking PhaZ depolymerase, confirmed the ability of Bdellovibrio to degrade the prey's PHA. Predator motility was higher when growing on PHA accumulating prey. External addition of PHA polymer (latex suspension) to Bdello- vibrio preying on the PHA minus mutant P. putida KT42C1 restored predator movement, suggesting that PHA is a key prey component to sustain predator swimming speed. High velocities observed in Bdello- vibrio preying on the PHA producing strain were cor- related to high intracellular ATP levels of the predator. These effects brought Bdellovibrio fitness benefits as predation on PHA producers was more efficient than predation on non-producing bacteria.
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Bdellovibrio exovorus sp nov a novel predator of caulobacter crescentus
International Journal of Systematic and Evolutionary Microbiology, 2013Co-Authors: Susan F. Koval, Ronald S Flannagan, Sandra H Hynes, Zohar Pasternak, Yaacov Davidov, Edouard JurkevitchAbstract:The life cycle, prey range and taxonomic status of a Bdellovibrio -like organism, strain JSST, were studied. Strain JSST was isolated from sewage in London, Ontario, Canada, in enrichment culture with Caulobacter crescentus prey cells. During predation, this strain remained attached to the outside of a stalked C. crescentus cell. No periplasmic growth stage was observed and no bdelloplast was formed. The stalked cells of C. crescentus retained their shape and, after predation, were devoid of cytoplasmic content, as shown by transmission electron microscopy. A periplasmic growth stage has been a definitive character in the description of members of the genera Bdellovibrio , Bacteriovorax , Bacteriolyticum and Peredibacter . This is the first description of an epibiotic predator in this group of prokaryotic predators. The G+C content of the genomic DNA of strain JSST was 46.1 mol%. 16S rRNA gene sequence analysis showed that this strain was related to Bdellovibrio bacteriovorus strains HD100T, 109J, 114 and 127 (90–93 % similarity). Phylogenetic analysis based on 16S rRNA gene sequences grouped strain JSST with the Bdellovibrio cluster, but at a distance from other Bdellovibrio isolates. On the basis of features of the life cycle and phylogenetic data, it was concluded that strain JSST merits classification as the type strain of a novel species, for which the name Bdellovibrio exovorus sp. nov. is proposed (type strain JSST = ATCC BAA-2330T = DSM 25223T).
Eileen M Spain - One of the best experts on this subject based on the ideXlab platform.
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identification and differential production of ubiquinone 8 in the bacterial predator Bdellovibrio bacteriovorus
Research in Microbiology, 2016Co-Authors: Eileen M Spain, Megan E Nunez, Hyeongjin Kim, Ryan J Taylor, Nicholas Thomas, Michael B Wengen, Nathan F Dalleska, Joseph P Bromley, Kimberly H Schermerhorn, Megan A FergusonAbstract:Bdellovibrio bacteriovorus 109J, a predatory bacterium with potential as a bacterial control agent, can exist in several lifestyles that differ both in predatory capacity and color. We determined that levels of ubiquinone-8 contribute to the distinctive but variable yellow color of different types of Bdellovibrio cells. Steady-state ubiquinone-8 concentrations did not differ markedly between conventional predatory and host-independent B. bacteriovorus despite upregulation of a suite of ubiquinone-8 synthesis genes in host-independent cells. In contrast, in spatially organized B. bacteriovorus films, the yellow inner regions contain significantly higher ubiquinone-8 concentrations than the off-white outer regions. Correspondingly, RT-PCR analysis reveals that the inner region, previously shown to consist primarily of active predators, clearly expresses two ubiquinone biosynthesis genes, while the outer region, composed mainly of quiescent or stalled bdelloplasts, expresses those genes weakly or not at all. Moreover, B. bacteriovorus cells in the inner region of week-old interfacial films, which are phenotypically attack-phase, have much higher UQ8 levels than regular attack-phase Bdellovibrios, most likely because their “trapped” state prevents a high expenditure of energy to power flagellar motion.
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quantitative changes in the elasticity and adhesive properties of escherichia coli zk1056 prey cells during predation by Bdellovibrio bacteriovorus 109j
Langmuir, 2008Co-Authors: Catherine B Volle, Eileen M Spain, Megan A Ferguson, Katherine E Aidala, Megan E NunezAbstract:Atomic force microscopy (AFM) was used to explore the changes that occur in Escherichia coli ZK1056 prey cells while they are being consumed by the bacterial predator Bdellovibrio bacteriovorus 109J. Invaded prey cells, called bdelloplasts, undergo substantial chemical and physical changes that can be directly probed by AFM. In this work, we probe the elasticity and adhesive properties of uninvaded prey cells and bdelloplasts in a completely native state in dilute aqueous buffer without chemical fixation. Under these conditions, the rounded bdelloplasts were shown to be shorter than uninvaded prey cells. More interestingly, the extension portions of force curves taken on both kinds of cells clearly demonstrate that bdelloplasts are softer than uninvaded prey cells, reflecting a decrease in bdelloplast elasticity after invasion by Bdellovibrio predators. On average, the spring constant of uninvaded E. coli cells (0.23 ± 0.02 N/m) was 3 times stiffer than that of the bdelloplast (0.064 ± 0.001 N/m) when mea...
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predation death and survival in a biofilm Bdellovibrio investigated by atomic force microscopy
Colloids and Surfaces B: Biointerfaces, 2005Co-Authors: Megan E Nunez, Mark O Martin, Phyllis H Chan, Eileen M SpainAbstract:Biofilms are complex microbial communities that are resistant to attack by bacteriophages and to removal by drugs and chemicals. Here we use atomic force microscopy (AFM) to image the attack on Escherichia coli biofilms by Bdellovibrio bacteriovorus 109J. Bdellovibrio is a small, predatory bacterium that invades and devours other Gram-negative bacteria. We demonstrate that under dilute nutrient conditions, Bdellovibrios can prevent the formation of simple bacterial biofilms and destroy established biofilms; under richer conditions the prey bacteria persist and are not eradicated, but may be shifted toward solution populations. Using AFM we explore these bacterial interactions with more detail and accuracy than available by more traditional staining assays or optical microscopy. AFM also allows us to investigate the nanoscale morphological changes of the predator, especially those related to motility. This demonstration of Bdellovibrio's successful predation in a biofilm inspires us to consider ways that it might be used productively for industrial, medical, agricultural, and biodefensive purposes.
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investigations into the life cycle of the bacterial predator Bdellovibrio bacteriovorus 109j at an interface by atomic force microscopy
Biophysical Journal, 2003Co-Authors: Megan E Nunez, Mark O Martin, Lin K Duong, Eileen M SpainAbstract:Atomic force microscopy was used to image Bdellovibrio bacteriovorus 109J, a gram-negative bacterial predator that consumes a variety of other gram-negative bacteria. In predator-prey communities grown on filters at hydrated air-solid interfaces, repeated cycles of hunting, invasion, growth, and lysis occurred readily even though the cells were limited to near two-dimensional movement. This system allowed us to image the bacteria directly without extensive preparation or modification, and many of the cells remained alive during imaging. Presented are images of the life cycle in two species of prey organisms, both Escherichia coli (a small prey bacterium that grows two-dimensionally on a surface) and Aquaspirillum serpens (a large prey bacterium that grows three-dimensionally on a surface), including high-resolution images of invaded prey cells called bdelloplasts. We obtained evidence for multiple invasions per prey cell, as well as significant heterogeneity in morphology of Bdellovibrios. Mutant host-independent Bdellovibrios were observed to have flagella and to excrete a coating that causes the predators to clump together on a surface. Most interestingly, changes in the texture of the cell surface membranes were measured during the course of the invasion cycle. Thus, coupled with our preparation method, atomic force microscopy allowed new observations to be made about Bdellovibrio at an interface. These studies raise important questions about the ways in which bacterial predation at interfaces (air-solid or liquid-solid) may be similar to or different from predation in solution.
Laura Hobley - One of the best experts on this subject based on the ideXlab platform.
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A small predatory core genome in the divergent marine Bacteriovorax marinus SJ and the terrestrial Bdellovibrio bacteriovorus
The ISME Journal, 2013Co-Authors: Lisa C Crossman, Laura Hobley, R. Elizabeth Sockett, Huan Chen, Ana-m Cerdeño-tárraga, Karen Brooks, Michael A Quail, Silvia A Pineiro, Stephen D Bentley, Julian ParkhillAbstract:Bacteriovorax marinus SJ is a predatory delta-proteobacterium isolated from a marine environment. The genome sequence of this strain provides an interesting contrast to that of the terrestrial predatory bacterium Bdellovibrio bacteriovorus HD100. Based on their predatory lifestyle, Bacteriovorax were originally designated as members of the genus Bdellovibrio but subsequently were re-assigned to a new genus and family based on genetic and phenotypic differences. B. marinus attaches to Gram-negative bacteria, penetrates through the cell wall to form a bdelloplast, in which it replicates, as shown using microscopy. Bacteriovorax is distinct, as it shares only 30% of its gene products with its closest sequenced relatives. Remarkably, 34% of predicted genes over 500 nt in length were completely unique with no significant matches in the databases. As expected, Bacteriovorax shares several characteristic loci with the other delta-proteobacteria. A geneset shared between Bacteriovorax and Bdellovibrio that is not conserved among other delta-proteobacteria such as Myxobacteria (which destroy prey bacteria externally via lysis), or the non-predatory Desulfo-bacteria and Geobacter species was identified. These 291 gene orthologues common to both Bacteriovorax and Bdellovibrio may be the key indicators of host-interaction predatory-specific processes required for prey entry. The locus from Bdellovibrio bacteriovorus is implicated in the switch from predatory to prey/host-independent growth. Although the locus is conserved in B. marinus , the sequence has only limited similarity. The results of this study advance understanding of both the similarities and differences between Bdellovibrio and Bacteriovorax and confirm the distant relationship between the two and their separation into different families.
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genome analysis of a simultaneously predatory and prey independent novel Bdellovibrio bacteriovorus from the river tiber supports in silico predictions of both ancient and recent lateral gene transfer from diverse bacteria
BMC Genomics, 2012Co-Authors: Carey Lambert, Laura Hobley, Rob Till, Thomas R Lerner, Sarah M Basford, Laura E Williams, David S Milner, Michael J CapenessAbstract:Evolution equipped Bdellovibrio bacteriovorus predatory bacteria to invade other bacteria, digesting and replicating, sealed within them thus preventing nutrient-sharing with organisms in the surrounding environment. Bdellovibrio were previously described as “obligate predators” because only by mutations, often in gene bd0108, are 1 in ~1x107 of predatory lab strains of Bdellovibrio converted to prey-independent growth. A previous genomic analysis of B. bacteriovorus strain HD100 suggested that predatory consumption of prey DNA by lytic enzymes made Bdellovibrio less likely than other bacteria to acquire DNA by lateral gene transfer (LGT). However the Doolittle and Pan groups predicted, in silico, both ancient and recent lateral gene transfer into the B. bacteriovorus HD100 genome. To test these predictions, we isolated a predatory bacterium from the River Tiber- a good potential source of LGT as it is rich in diverse bacteria and organic pollutants- by enrichment culturing with E. coli prey cells. The isolate was identified as B. bacteriovorus and named as strain Tiberius. Unusually, this Tiberius strain showed simultaneous prey-independent growth on organic nutrients and predatory growth on live prey. Despite the prey-independent growth, the homolog of bd0108 did not have typical prey-independent-type mutations. The dual growth mode may reflect the high carbon content of the river, and gives B. bacteriovorus Tiberius extended non-predatory contact with the other bacteria present. The HD100 and Tiberius genomes were extensively syntenic despite their different cultured-terrestrial/freshly-isolated aquatic histories; but there were significant differences in gene content indicative of genomic flux and LGT. Gene content comparisons support previously published in silico predictions for LGT in strain HD100 with substantial conservation of genes predicted to have ancient LGT origins but little conservation of AT-rich genes predicted to be recently acquired. The natural niche and dual predatory, and prey-independent growth of the B. bacteriovorus Tiberius strain afforded it extensive non-predatory contact with other marine and freshwater bacteria from which LGT is evident in its genome. Thus despite their arsenal of DNA-lytic enzymes; Bdellovibrio are not always predatory in natural niches and their genomes are shaped by acquiring whole genes from other bacteria.
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mutagenesis of rpoe like sigma factor genes in Bdellovibrio reveals differential control of groel and two groes genes
BMC Microbiology, 2012Co-Authors: Carey Lambert, Laura Hobley, Rob Till, Elizabeth R SockettAbstract:Bdellovibrio bacteriovorus HD100 must regulate genes in response to a variety of environmental conditions as it enters, preys upon and leaves other bacteria, or grows axenically without prey. In addition to “housekeeping” sigma factors, its genome encodes several alternate sigma factors, including 2 Group IV-RpoE-like proteins, which may be involved in the complex regulation of its predatory lifestyle. We find that one sigma factor gene, bd3314, cannot be deleted from Bdellovibrio in either predatory or prey-independent growth states, and is therefore possibly essential, likely being an alternate sigma 70. Deletion of one of two Group IV-like sigma factor genes, bd0881, affects flagellar gene regulation and results in less efficient predation, although not due to motility changes; deletion of the second, bd0743, showed that it normally represses chaperone gene expression and intriguingly we find an alternative groES gene is expressed at timepoints in the predatory cycle where intensive protein synthesis at Bdellovibrio septation, prior to prey lysis, will be occurring. We have taken the first step in understanding how alternate sigma factors regulate different processes in the predatory lifecycle of Bdellovibrio and discovered that alternate chaperones regulated by one of them are expressed at different stages of the lifecycle.
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discrete cyclic di gmp dependent control of bacterial predation versus axenic growth in Bdellovibrio bacteriovorus
PLOS Pathogens, 2012Co-Authors: Laura Hobley, Carey Lambert, Robert Till, Rowena K Y Fung, Maximilian A T S Harris, Jayesh M Dabhi, Simon S King, Sarah M Basford, Kaoru Uchida, Rashidah AhmadAbstract:Bdellovibrio bacteriovorus is a Delta-proteobacterium that oscillates between free-living growth and predation on Gram-negative bacteria including important pathogens of man, animals and plants. After entering the prey periplasm, killing the prey and replicating inside the prey bdelloplast, several motile B. bacteriovorus progeny cells emerge. The B. bacteriovorus HD100 genome encodes numerous proteins predicted to be involved in signalling via the secondary messenger cyclic di-GMP (c-di-GMP), which is known to affect bacterial lifestyle choices. We investigated the role of c-di-GMP signalling in B. bacteriovorus, focussing on the five GGDEF domain proteins that are predicted to function as diguanylyl cyclases initiating c-di-GMP signalling cascades. Inactivation of individual GGDEF domain genes resulted in remarkably distinct phenotypes. Deletion of dgcB (Bd0742) resulted in a predation impaired, obligately axenic mutant, while deletion of dgcC (Bd1434) resulted in the opposite, obligately predatory mutant. Deletion of dgcA (Bd0367) abolished gliding motility, producing bacteria capable of predatory invasion but unable to leave the exhausted prey. Complementation was achieved with wild type dgc genes, but not with GGAAF versions. Deletion of cdgA (Bd3125) substantially slowed predation; this was restored by wild type complementation. Deletion of dgcD (Bd3766) had no observable phenotype. In vitro assays showed that DgcA, DgcB, and DgcC were diguanylyl cyclases. CdgA lacks enzymatic activity but functions as a c-di-GMP receptor apparently in the DgcB pathway. Activity of DgcD was not detected. Deletion of DgcA strongly decreased the extractable c-di-GMP content of axenic Bdellovibrio cells. We show that c-di-GMP signalling pathways are essential for both the free-living and predatory lifestyles of B. bacteriovorus and that obligately predatory dgcC- can be made lacking a propensity to survive without predation of bacterial pathogens and thus possibly useful in anti-pathogen applications. In contrast to many studies in other bacteria, Bdellovibrio shows specificity and lack of overlap in c-di-GMP signalling pathways.
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effects of orally administered Bdellovibrio bacteriovorus on the well being and salmonella colonization of young chicks
Applied and Environmental Microbiology, 2011Co-Authors: Robert J Atterbury, Carey Lambert, Andy Fenton, Laura Hobley, Thomas R Lerner, Michael J Capeness, Robert Till, Paul A Barrow, Elizabeth R SockettAbstract:Bdellovibrio bacteriovorus is a bacterium which preys upon and kills Gram-negative bacteria, including the zoonotic pathogens Escherichia coli and Salmonella. Bdellovibrio has potential as a biocontrol agent, but no reports of it being tested in living animals have been published, and no data on whether Bdellovibrio might spread between animals are available. In this study, we tried to fill this knowledge gap, using B. bacteriovorus HD100 doses in poultry with a normal gut microbiota or predosed with a colonizing Salmonella strain. In both cases, Bdellovibrio was dosed orally along with antacids. After dosing non-Salmonella-infected birds with Bdellovibrio, we measured the health and well-being of the birds and any changes in their gut pathology and culturable microbiota, finding that although a Bdellovibrio dose at 2 days of age altered the overall diversity of the natural gut microbiota in 28-day-old birds, there were no adverse effects on their growth and well-being. Drinking water and fecal matter from the pens in which the birds were housed as groups showed no contamination by Bdellovibrio after dosing. Predatory Bdellovibrio orally administered to birds that had been predosed with a gut-colonizing Salmonella enterica serovar Enteritidis phage type 4 strain (an important zoonotic pathogen) significantly reduced Salmonella numbers in bird gut cecal contents and reduced abnormal cecal morphology, indicating reduced cecal inflammation, compared to the ceca of the untreated controls or a nonpredatory ΔpilA strain, suggesting that these effects were due to predatory action. This work is a first step to applying Bdellovibrio therapeutically for other animal, and possibly human, infections.