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1.
Appl Microbiol Biotechnol ; 108(1): 422, 2024 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-39031211

RESUMO

Identifying the nutritional requirements and growth conditions of microorganisms is crucial for determining their applicability in industry and understanding their role in clinical ecology. Predatory bacteria such as Bdellovibrio bacteriovorus have emerged as promising tools for combating infections by human bacterial pathogens due to their natural killing features. Bdellovibrio's lifecycle occurs inside prey cells, using the cytoplasm as a source of nutrients and energy. However, this lifecycle supposes a challenge when determining the specific uptake of metabolites from the prey to complete the growth inside cells, a process that has not been completely elucidated. Here, following a model-based approach, we illuminate the ability of B. bacteriovorus to replicate DNA, increase biomass, and generate adenosine triphosphate (ATP) in an amino acid-based rich media in the absence of prey, keeping intact its predatory capacity. In this culture, we determined the main carbon sources used and their preference, being glutamate, serine, aspartate, isoleucine, and threonine. This study offers new insights into the role of predatory bacteria in natural environments and establishes the basis for developing new Bdellovibrio applications using appropriate metabolic and physiological methodologies. KEY POINTS: • Amino acids support axenic lifestyle of Bdellovibrio bacteriovorus. • B. bacteriovorus preserves its predatory ability when growing in the absence of prey.


Assuntos
Trifosfato de Adenosina , Aminoácidos , Bdellovibrio bacteriovorus , Carbono , Aminoácidos/metabolismo , Carbono/metabolismo , Bdellovibrio bacteriovorus/metabolismo , Bdellovibrio bacteriovorus/fisiologia , Trifosfato de Adenosina/metabolismo , Meios de Cultura/química , Biomassa
2.
J Tissue Viability ; 32(4): 541-549, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37558561

RESUMO

Bdellovibrio bacteriovorus is a bacterial agent that stands out for its ability to act as a predator against gram-negative bacteria and has found application against antibiotic-resistant pathogens. The aim of this study is to determine the efficacy of Bdellovibrio bacteriovorus against antibiotic-resistant pathogens, particularly those causing infections in surgical incision sites. A total of 6 experimental groups were created in mice, and surgical area infections were initiated with Klebsiella pneumoniae in incision sites. The effects of antibiotics and Bdellovibrio bacteriovorus alone or in combination were compared to the control group. In the Bdellovibrio bacteriovorus treatment group, edema and redness were observed in all mice at 24th hours, in 20% of mice at 48th hours, and in none at the 72 nd h. A significant difference was observed in the Bdellovibrio bacteriovorus treatment groups in reducing Klebsiella pneumoniae burden in the incision area compared to antibiotics alone or Bdellovibrio bacteriovorus + antibiotics, (p < 0.001). Likewise, cytokine level determinations indicated that B. bacteriovorus applications generated a therapeutic response without inducing an inflammatory response.


Assuntos
Bdellovibrio bacteriovorus , Camundongos , Animais , Bdellovibrio bacteriovorus/fisiologia , Klebsiella pneumoniae/fisiologia , Infecção da Ferida Cirúrgica , Bandagens , Antibacterianos
3.
Biophys J ; 122(15): 3060-3068, 2023 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-37330639

RESUMO

Bdellovibrio bacteriovorus is a predatory bacterium preying upon Gram-negative bacteria. As such, B. bacteriovorus has the potential to control antibiotic-resistant pathogens and biofilm populations. To survive and reproduce, B. bacteriovorus must locate and infect a host cell. However, in the temporary absence of prey, it is largely unknown how B. bacteriovorus modulate their motility patterns in response to physical or chemical environmental cues to optimize their energy expenditure. To investigate B. bacteriovorus' predation strategy, we track and quantify their motion by measuring speed distributions as a function of starvation time. While an initial unimodal speed distribution relaxing to one for pure diffusion at long times may be expected, instead we observe a bimodal speed distribution with one mode centered around that expected from diffusion and the other centered at higher speeds. What is more, for an increasing amount of time over which B. bacteriovorus is starved, we observe a progressive reweighting from the active swimming state to an apparent diffusive state in the speed distribution. Distributions of trajectory-averaged speeds for B. bacteriovorus are largely unimodal, indicating switching between a faster swim speed and an apparent diffusive state within individual observed trajectories rather than there being distinct active swimming and apparent diffusive populations. We also find that B. bacteriovorus' apparent diffusive state is not merely caused by the diffusion of inviable bacteria as subsequent spiking experiments show that bacteria can be resuscitated and bimodality restored. Indeed, starved B. bacteriovorus may modulate the frequency and duration of active swimming as a means of balancing energy consumption and procurement. Our results thus point to a reweighting of the swimming frequency on a trajectory basis rather than a population level basis.


Assuntos
Bdellovibrio bacteriovorus , Natação , Sinais (Psicologia) , Bdellovibrio bacteriovorus/fisiologia , Bactérias , Biofilmes
4.
Burns ; 49(5): 1181-1195, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36116995

RESUMO

Owing to the high level of resistance to various antibiotics in bacteria causing burn wound infections, the alternative therapeutics is highly demanded. Bdellovibrio and like organisms (BALOs) seem to be a superb choice. In the present study, Bdellovibrio bacteriovorus HD100 was selected for treating burn wound infection caused by Pseudomonas aeruginosa strain PAO1 in a mouse model. In this experiment, two treatments, meropenem as antibiotic and B. bacteriovorus, were employed. Histopathology indicated an accelerated healing rate in both treatments in comparison with the control. Moreover, quantitative reverse transcription PCR (qRT-PCR) was applied to investigate the expression of tnf-α (tumor necrosis factor alpha), pdgf (platelet-derived growth factor), tgf-ß1 (transforming growth factor beta1), ifn-γ (interferon gamma), vegf (vascular endothelial group factor), and col1 (collagen type 1). The results demonstrated that treating burn wound areas with Bdellovibrio not only decrease the inflammatory phase period, but also may improve the characteristics of proliferative phases of wound healing. In addition, a significant difference was explored between the two treatment groups in the regulation of all genes, except for pdgf revealed a significant up regulation in both treatment groups. The results disclose that Bdellovibrio attenuates P. aeruginosa in burn wounds infections and improves the wound healing process.


Assuntos
Bdellovibrio bacteriovorus , Bdellovibrio , Queimaduras , Infecção dos Ferimentos , Animais , Camundongos , Bdellovibrio bacteriovorus/fisiologia , Queimaduras/terapia , Bdellovibrio/genética , Pseudomonas , Infecção dos Ferimentos/terapia
5.
Microbiol Spectr ; 10(6): e0309422, 2022 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-36445149

RESUMO

Bdellovibrio and like organisms (BALOs) are a unique bacterial group that live by predating on other bacteria, consuming them from within to grow and replicate before the progeny come out to complete the life cycle. The mechanisms by which these predators recognize their prey and differentiate them from nonprey bacteria, however, are still not clear. Through genetic knockout and complementation studies in different Escherichia coli strains, we found that Bdellovibrio bacteriovorus strain 109J recognizes outer membrane porin F (OmpF) on the E. coli surface and that the activity of the E. coli EnvZ-OmpR regulatory system significantly impacts predation kinetics. OmpF is not the only signal by which BALOs recognize their prey, however, as B. bacteriovorus could eventually predate on the E. coli ΔompF mutant after prolonged incubation. Furthermore, recognizing OmpF as a prey surface structure was dependent on the prey strain, as knocking out OmpF protein homologues in other prey species, including Escherichia fergusonii, Klebsiella pneumoniae, and Salmonella enterica, did not always reduce the predation rate. Consequently, although OmpF was found to be an important surface component used by Bdellovibrio to efficiently recognize and attack E. coli, future work is needed to determine what other prey surface structures are recognized by these predators. IMPORTANCE Bdellovibrio bacteriovorus and like organisms (BALOs) are Gram-negative predatory bacteria that attack other Gram-negative bacteria by penetrating their periplasm and consuming them from within to obtain the nutrients necessary for the predator's growth and replication. How these predators recognize their prey, however, has remained a mystery. Here, we show that the outer membrane porin F (OmpF) in E. coli is recognized by B. bacteriovorus strain 109J and that the loss of this protein leads to severely delayed predation. However, predation of several other prey species was not dependent on the recognition of this protein or its homologues, indicating that there are other structures recognized by the predators on the prey surface that are yet to be discovered.


Assuntos
Bdellovibrio bacteriovorus , Escherichia coli , Porinas , Bdellovibrio bacteriovorus/fisiologia , Escherichia coli/genética , Escherichia coli/metabolismo , Porinas/genética , Porinas/metabolismo
6.
Microbiol Spectr ; 10(1): e0103321, 2022 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-35196816

RESUMO

Bdellovibrio bacteriovorus is a predatory, Gram-negative bacteria that feeds on many pathogenic bacteria and has been investigated as a possible solution for mitigating biofilms in different fields. The application depends on more fundamental ecological studies into the dynamics between Bdellovibrio and their prey. To do so requires an accurate, reliable, and, preferably rapid, way of enumerating the cells. Flow cytometry (FCM) is potentially a rapid, accurate, and inexpensive tool for this, but it has yet to be validated in the enumeration of Bdellovibrio. In this study, we developed a protocol to measure the number of Bdellovibrio in samples of various densities using FCM and compared the results with those of other methods: optical density (OD), PFU assay (PFU), and quantitative PCR (qPCR). We observed a strong correlation between values obtained using FCM and PFU (ρ = 0.923) and FCM and qPCR (ρ = 0.987). Compared to optical density there was a much weaker correlation (ρ = 0.784), which was to be expected given the well-documented uncertainty in converting optical density (OD) to cell numbers. The FCM protocol was further validated by demonstrating its ability to distinguish and count mixed populations of Bdellovibrio and the prey Pseudomonas. Thus, the accuracy of FCM as well as its speed and reproducibility make it a suitable alternative for measuring Bdellovibrio cell numbers, especially where many samples are required to capture the dynamics of predator-prey interactions. IMPORTANCE The rise of antibiotic resistance and the unwanted growth of bacteria is a universally growing problem. Predatory bacteria can be used as a biological alternative to antibiotics because they grow by feeding on other bacteria. To apply this effectively requires further study and a deeper understanding of the forces that drive a prey population to elimination. Initially, such studies require more reliable methods to count these cells. Flow cytometry (FCM) is potentially a rapid, accurate, and inexpensive tool for this, but it has yet to be validated for predatory bacteria. This study develops a protocol to count the predatory bacteria Bdellovibrio bacteriovorus and its Pseudomonas prey using FCM and compare the results with those of other methods, demonstrating its ability for studies into B. bacteriovorus predation dynamics. This could lead to the use of B. bacteriovorus for killing bacterial biofilms in fields, such as drinking water and agriculture.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Citometria de Fluxo/métodos , Pseudomonas/metabolismo , Biofilmes
7.
STAR Protoc ; 3(1): 101104, 2022 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-35098160

RESUMO

The predatory bacterium Bdellovibrio bacteriovorus invades and proliferates inside other bacteria by non-binary division. Here we describe a fluorescence-based technique for the immediate evaluation of predator density independently of plaque formation, an optimized setup to monitor predation in microplates, and the CuRveR package to quantify both prey killing and predator proliferation dynamics. This protocol allows to assess the impact of mutations or chemicals on predation. CuRveR also constitutes a user-friendly tool to analyze growth or decay data unrelated to predation. For complete details on the use and execution of this profile, please refer to Kaljevic et al., 2021.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Comportamento Predatório , Animais , Fluxo de Trabalho
8.
Adv Sci (Weinh) ; 8(21): e2102327, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34494724

RESUMO

The development of potent antibiotic alternatives with rapid bactericidal properties is of great importance in addressing the current antibiotic crisis. One representative example is the topical delivery of predatory bacteria to treat ocular bacterial infections. However, there is a lack of suitable methods for the delivery of predatory bacteria into ocular tissue. This work introduces cryomicroneedles (cryoMN) for the ocular delivery of predatory Bdellovibrio bacteriovorus (B. bacteriovorus) bacteria. The cryoMN patches are prepared by freezing B. bacteriovorus containing a cryoprotectant medium in a microneedle template. The viability of B. bacteriovorus in cryoMNs remains above 80% as found in long-term storage studies, and they successfully impede the growth of gram-negative bacteria in vitro or in a rodent eye infection model. The infection is significantly relieved by nearly six times through 2.5 days of treatment without substantial effects on the cornea thickness and morphology. This approach represents the safe and efficient delivery of new class of antimicrobial armamentarium to otherwise impermeable ocular surface and opens up new avenues for the treatment of ocular surface disorders.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Infecções Oculares/microbiologia , Injeções Intraoculares/métodos , Administração Tópica , Animais , Bdellovibrio bacteriovorus/crescimento & desenvolvimento , Córnea/anatomia & histologia , Córnea/fisiologia , Modelos Animais de Doenças , Infecções Oculares/diagnóstico por imagem , Infecções Oculares/terapia , Bactérias Gram-Negativas/fisiologia , Injeções Intraoculares/instrumentação , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Agulhas , Tomografia de Coerência Óptica
9.
Res Microbiol ; 172(7-8): 103878, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34492337

RESUMO

Bdellovibrio bacteriovorus, a Gram-negative predatory bacterium belonging to the Bdellovibrio and like organisms (BALOs), predates on Gram-negative bacteria. BALO strains differ in prey range but so far, the genetic basis of resistance against BALO predation is hardly understood. We developed a loss-of-function approach to screen for sensitive mutants in a library of strain M6, a predation-resistant strain of the plant pathogen Acidovorax citrulli. The screen is based on tracking the growth of a B. bacteriovorus strain expressing the fluorescent reporter Tdtomato in mutant pools to reveal predation-sensitive variants. Two independent loci were identified in mutant strains exhibiting significant levels of susceptibility to the predator. Genes in the two loci were analysed using both protein sequence homology and protein structure modeling. Both were secretion-related proteins and thus associated to the bacterial cell wall. Successful complementation of gspK, a gene encoding for a minor pseudopilin protein confirmed the involvement of the type II secretion system in A. citrulli M6 resistance. This proof of concept study shows that our approach can identify key elements of the BALO-prey interaction, and it validates the hypothesis that mutational changes in a single gene can drastically impact prey resistance to BALO predation.


Assuntos
Proteínas de Bactérias/metabolismo , Bdellovibrio bacteriovorus/fisiologia , Comamonadaceae/fisiologia , Interações Microbianas , Sistemas de Secreção Tipo II/fisiologia , Proteínas de Bactérias/genética , Bdellovibrio bacteriovorus/crescimento & desenvolvimento , Comamonadaceae/genética , Genes Bacterianos , Mutagênese Insercional , Mutação , Sistemas de Secreção Tipo II/genética
10.
Int Microbiol ; 24(3): 399-413, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33956240

RESUMO

Bdellovibrios are predatory bacteria that invade other live Gram-negative bacterial cells for growth and reproduction. They have recently been considered as potential living antibiotics and biocontrol agents. In this study, the predatory activity and biocontrol potency of Bdellovibrio bacteriovorus strain SOIR-1 against Pantoea sp. strain BCCS and Xanthomonas campestris, two exo-biopolymer-producing phytopathogens, was evaluated. Plaque formation assays and lysis analysis in the broth co-cultures were used for the in vitro evaluation of bacteriolytic activity of strain SOIR-1. The in vivo biocontrol potential of strain SOIR-1 was evaluated by pathogenicity tests on the onion bulbs and potato tuber slices. The phytopathogens were also recovered from the infected plant tissues and confirmed using biochemical tests and PCR-based 16S rRNA gene sequence analysis. Typical bdellovibrios plaques were developed on the lawn cultures of Pantoea sp. BCCS and X. campestris. The killing rate of strain SOIR-1 toward Pantoea sp. BCCS and X. campestris was 84.3% and 76.3%, respectively. Exo-biopolymers attenuated the predation efficiency of strain SOIR-1 up to 10.2-18.2% (Pantoea sp. BCCS) and 12.2-17.3% (X. campestris). The strain SOIR-1 significantly reduced rotting symptoms in the onion bulbs caused by Pantoea sp. BCCS (69.0%) and potato tuber slices caused by X. campestris (73.1%). Although more field assessments are necessary, strain SOIR-1 has the preliminary potential as a biocontrol agent against phytopathogenic Pantoea sp. BCCS and X. campestris, especially in postharvest storage. Due to the particular physicochemical properties of evaluated exo-biopolymers, they can be used in the designing encapsulation systems for delivery of bdellovibrios.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Bdellovibrio bacteriovorus/patogenicidade , Agentes de Controle Biológico/farmacologia , Pantoea/efeitos dos fármacos , Pantoea/fisiologia , Xanthomonas campestris/efeitos dos fármacos , Xanthomonas campestris/fisiologia , Antibiose , Biopolímeros/fisiologia , Técnicas de Cocultura/métodos , DNA Bacteriano , Interações Microbianas , RNA Ribossômico 16S
11.
Crit Rev Microbiol ; 47(5): 630-646, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33934682

RESUMO

Bdellovibrio bacteriovorus is a small Deltaproteobacterium which, since its discovery, has distinguished itself for the unique ability to prey on other Gram-negative bacteria. The studies on this particular "predatory bacterium", have gained momentum in response to the rising problem of antibiotic resistance, because it could be applied as a potential probiotic and antibiotic agent. Hereby, we present recent advances in the study of B. bacteriovorus, comprehending fundamental aspects of its biology, obligatory intracellular life cycle, predation resistance, and potential applications. Furthermore, we discuss studies that pave the road towards the use of B. bacteriovorus as a "living antibiotic" in human therapy, focussing on its interaction with biofilms, the host immune response, predation susceptibility and in vivo application models. The available data imply that it will be possible to upgrade this predator bacterium from a predominantly academic interest to an instrument that could confront antibiotic resistant infections.


Assuntos
Antibiose , Infecções Bacterianas/terapia , Bdellovibrio bacteriovorus/fisiologia , Bactérias Gram-Negativas/fisiologia , Bactérias Gram-Positivas/fisiologia , Animais , Infecções Bacterianas/microbiologia , Bdellovibrio bacteriovorus/crescimento & desenvolvimento , Biofilmes/crescimento & desenvolvimento , Agentes de Controle Biológico , Farmacorresistência Bacteriana , Bactérias Gram-Negativas/efeitos dos fármacos , Interações Microbianas , Probióticos
12.
Microbiology (Reading) ; 167(4)2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33843574

RESUMO

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.


Assuntos
Antibiose , Bdellovibrio bacteriovorus/fisiologia , Bactérias , Fenômenos Fisiológicos Bacterianos , Bdellovibrio bacteriovorus/classificação , Bdellovibrio bacteriovorus/genética , Bdellovibrio bacteriovorus/isolamento & purificação , Genoma Bacteriano , Filogenia , Microbiologia do Solo
13.
Microbiology (Reading) ; 167(1)2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33465024

RESUMO

Antimicrobial resistance (AMR) is a global health and economic crisis. With too few antibiotics in development to meet current and anticipated needs, there is a critical need for new therapies to treat Gram-negative infections. One potential approach is the use of living predatory bacteria, such as Bdellovibrio bacteriovorus (small Gram-negative bacteria that naturally invade and kill Gram-negative pathogens of humans, animals and plants). Moving toward the use of Bdellovibrio as a 'living antibiotic' demands the investigation and characterization of these bacterial predators in biologically relevant systems. We review the fundamental science supporting the feasibility of predatory bacteria as alternatives to antibiotics.


Assuntos
Antibiose , Bdellovibrio bacteriovorus/fisiologia , Bactérias Gram-Positivas/fisiologia , Animais , Antibacterianos/farmacologia , Bdellovibrio bacteriovorus/genética , Farmacorresistência Bacteriana , Bactérias Gram-Positivas/efeitos dos fármacos , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos
14.
Microb Ecol ; 81(2): 347-356, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32892232

RESUMO

Bdellovibrio bacteriovorus 109J is a predatory bacterium which lives by predating on other Gram-negative bacteria to obtain the nutrients it needs for replication and survival. Here, we evaluated the effects two classes of bacterial signaling molecules (acyl homoserine lactones (AHLs) and diffusible signaling factor (DSF)) have on B. bacteriovorus 109J behavior and viability. While AHLs had a non-significant impact on predation rates, DSF considerably delayed predation and bdelloplast lysis. Subsequent experiments showed that 50 µM DSF also reduced the motility of attack-phase B. bacteriovorus 109J cells by 50% (38.2 ± 14.9 vs. 17 ± 8.9 µm/s). Transcriptomic analyses found that DSF caused genome-wide changes in B. bacteriovorus 109J gene expression patterns during both the attack and intraperiplasmic phases, including the significant downregulation of the flagellum assembly genes and numerous serine protease genes. While the former accounts for the reduced speeds observed, the latter was confirmed experimentally with 50 µM DSF completely blocking protease secretion from attack-phase cells. Additional experiments found that 30% of the total cellular ATP was released into the supernatant when B. bacteriovorus 109J was exposed to 200 µM DSF, implying that this QS molecule negatively impacts membrane integrity.


Assuntos
Bdellovibrio bacteriovorus/efeitos dos fármacos , Ácidos Graxos Monoinsaturados/toxicidade , Percepção de Quorum , 4-Butirolactona/análogos & derivados , 4-Butirolactona/toxicidade , Antibiose/efeitos dos fármacos , Bdellovibrio bacteriovorus/genética , Bdellovibrio bacteriovorus/metabolismo , Bdellovibrio bacteriovorus/fisiologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Flagelos/genética , Serina Proteases/genética , Serina Proteases/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos
15.
Curr Opin Microbiol ; 56: 74-80, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32784086

RESUMO

Bacterial predation, as exemplified by the periplasm-invading model predator Bdellovibrio bacteriovorus, is a fascinating multistage process facilitated by several adaptations to 'regular' bacterial lifestyles. We are beginning to understand more about such adaptations at the molecular level, particularly those concerning processes near the beginning of the predatory lifecycle (recognition, invasion, prey cell wall manipulation). In this review we highlight recent advances in investigating predation and tie these into some of the classical observations and phenotypes that make this two-cell system such an interesting case study in evolution.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Bactérias/genética , Fenômenos Fisiológicos Bacterianos , Bdellovibrio bacteriovorus/genética , Evolução Biológica , Regulação Bacteriana da Expressão Gênica
16.
Environ Microbiol ; 22(2): 694-704, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31814273

RESUMO

Natural landscapes are both fragmented and heterogeneous, affecting the distribution of organisms, and their interactions. While predation in homogeneous environments increases the probability of population extinction, fragmentation/heterogeneity promotes coexistence and enhances community stability as shown by experimentation with animals and microorganisms, and supported by theory. Patch connectivity can modulate such effects but how microbial predatory interactions are affected by water-driven connectivity is unknown. In soil, patch habitability by microorganisms, and their connectivity depend upon the water saturation degree (SD). Here, using the obligate bacterial predator Bdellovibrio bacteriovorus, and a Burkholderia prey, we show that soil spatial heterogeneity profoundly affects predatory dynamics, enhancing long-term co-existence of predator and prey in a SD-threshold dependent-manner. However, as patches and connectors cannot be distinguished in these soil matrices, metapopulations cannot be invoked to explain the dynamics of increased persistence. Using a set of experiments combined with statistical and physical models we demonstrate and quantify how under full connectivity, predation is independent of water content but depends on soil microstructure characteristics. In contrast, the SD below which predation is largely impaired corresponds to a threshold below which the water network collapses and water connectivity breaks down, preventing the bacteria to move within the soil matrix.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Burkholderia/fisiologia , Interações Microbianas/fisiologia , Comportamento Predatório/fisiologia , Animais , Modelos Teóricos , Microbiologia do Solo
17.
Environ Microbiol ; 21(12): 4675-4684, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31498968

RESUMO

Bdellovibrio bacteriovorus HD100 is a highly motile predatory bacterium that consumes other Gram-negative bacteria for its sustenance. Here, we describe the impacts the media viscosity has both on the motility of predator and its attack rates. Experiments performed in polyethylene glycol (PEG) solutions, a linear polymer, found a viscosity of 10 mPa s (5% PEG) negatively impacted predation over a 24-h period. When the viscosity was increased to 27 mPa s (10% PEG), predation was nearly abolished. Tests with three other B. bacteriovorus strains, i.e., 109J and two natural isolates, found identical results. Short-term (2-h) experiments, however, found attack rates were improved in 1% PEG, which had a viscosity of 5.4 mPa s, using bioluminescent prey and their viabilities. In contrast, when experiments were performed in dextran, a branched polymer, no increase in predation was seen even though the viscosity was a comparable 5.1 mPa s. The enhanced attack rates in this solution coincided with a 31% increase in B. bacteriovorus HD100 swimming speeds (62 µm s-1 in 1% PEG vs. 47.5 µm s-1 in HEPES-salt).


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Meios de Cultura/química , Bdellovibrio bacteriovorus/efeitos dos fármacos , Meios de Cultura/metabolismo , Dextranos/química , Dextranos/farmacologia , Bactérias Gram-Negativas , Polietilenoglicóis/química , Polietilenoglicóis/farmacologia , Viscosidade
18.
Microbiol Res ; 228: 126305, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31422234

RESUMO

Traditional culture-based enumeration methods were compared with the ethidium monoazide quantitative polymerase chain reaction (EMA-qPCR) technique to assess Bdellovibrio-and-like-organisms (BALOs) predator-prey interactions. Gram-negative [Pseudomonas spp. and Klebsiella pneumoniae (K. pneumoniae)] and Gram-positive [Staphylococcus aureus (S. aureus) and Enterococcus faecium (E. faecium)] organisms were employed as prey cells, while a Bdellovibrio bacteriovorus strain (PF13) was used as the predator. The co-culture experiments were also compared in diluted nutrient broth (DNB) and HEPES buffer. In both media, K. pneumoniae (maximum log reduction of 5.13) and Pseudomonas fluorescens (P. fluorescens) (maximum log reduction of 4.21) were sensitive to predation by B. bacteriovorus PF13 as their cell counts and gene copies were reduced during all the co-culture experiments, while the concentration of B. bacteriovorus PF13 increased. The concentration of B. bacteriovorus PF13 also increased in the presence of S. aureus (HEPES buffer) and E. faecium (DNB), indicating that the predator interacted with these Gram-positive prey in order to survive. Moreover, as no predator plaques were produced in the co-culture experiments with P. aeruginosa (DNB and HEPES buffer), S. aureus (DNB and HEPES buffer) and E. faecium (HEPES buffer), EMA-qPCR proved to be beneficial in monitoring the concentration of B. bacteriovorus. In conclusion, the cell counts and/or EMA-qPCR analysis for the HEPES buffer and DNB assays were successfully employed to monitor the predation of P. fluorescens and K. pneumoniae by B. bacteriovorus, while E. faecium was sensitive to predation in DNB and S. aureus was sensitive to predation in HEPES buffer.


Assuntos
Azidas , Fenômenos Fisiológicos Bacterianos , Interações Microbianas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Bactérias , Bdellovibrio bacteriovorus/fisiologia , Técnicas de Cocultura , Contagem de Colônia Microbiana , Enterococcus faecium/fisiologia , Klebsiella pneumoniae/fisiologia , Pseudomonas/fisiologia , Staphylococcus aureus/fisiologia , Águas Residuárias/microbiologia , Purificação da Água
19.
Appl Environ Microbiol ; 85(14)2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31076424

RESUMO

Bdellovibrio bacteriovorus is 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 of B. bacteriovorus consists of two phases: a free-living nonreplicative attack phase, in which the predatory bacterium searches for its prey, and a reproductive phase, in which B. bacteriovorus degrades 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 of B. bacteriovorus Our results show that in B. 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 this B. bacteriovorus life cycle fails in some cells of Escherichia coli, they can instead use second prey cells to complete their life cycle.IMPORTANCE New strategies are needed to combat multidrug-resistant bacterial infections. Application of the predatory bacterium Bdellovibrio bacteriovorus, which kills other bacteria, including pathogens, is considered promising for combating bacterial infections. The B. bacteriovorus life 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 of B. bacteriovorus as 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 of B. bacteriovorus This process initiates at the invasion pole of B. bacteriovorus and proceeds until several copies of the chromosome have been completely synthesized. Interestingly, we demonstrate that some cells of B. bacteriovorus require two prey cells sequentially to complete their life cycle.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Período de Replicação do DNA , Características de História de Vida , Bdellovibrio bacteriovorus/genética , Dieta
20.
Sci Rep ; 9(1): 7225, 2019 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-31076594

RESUMO

With the rise of antimicrobial resistance, novel ways to treat bacterial infections are required and the use of predatory bacteria may be one such approach. Bdellovibrio species have been shown in vitro to predate on a wide range of other Gram-negative bacteria, including CDC category A/B pathogens such as Yersinia pestis. The data reported here show that treatment of SKH-1 mice with Bdellovibrio bacteriovorus HD100 provided significant protection from a lethal challenge of Yersinia pestis CO92. This is the first report of protection conferred by predation in vivo against a systemic pathogen challenge. However, this protective effect was not observed in a preliminary study with Balb/c mice. Therefore the effects of the predatory bacteria are complex and may be dependent on immune status/genetics of the host. Overall, predatory bacteria may have utility as a therapeutic modality but further work is required to understand the predator-host interaction.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Peste/prevenção & controle , Yersinia pestis/patogenicidade , Animais , Modelos Animais de Doenças , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Imagem Óptica , Fagocitose , Peste/microbiologia , Peste/patologia
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