Attack-Phase Bdellovibrio bacteriovorus Responses to Extracellular Nutrients Are Analogous to Those Seen During Late Intraperiplasmic Growth

Dwidar, Mohammed; Im, Hansol; Seo, Jeong Kon; Mitchell, Robert J.

doi:10.1007/s00248-017-1003-1

Cited by 23 publications

(22 citation statements)

References 39 publications

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“…When viewed alongside the findings of Dwidar et al [18], where B. bacteriovorus HD100 altered its transcriptome and secreted proteases in response to nutrients in the form of nutrient broth, the above results imply B. bacteriovorus HD100 also responds to S. aureus biofilms as if they were a source of amino acids and secretes proteases in reply. This was confirmed by both the transcriptomic data, where the expression levels for several different serine protease genes were elevated when B. bacteriovorus HD100 was exposed to the S. aureus biofilms for 4 h ( Figure S5), and the increased extracellular proteolytic activities, which paralleled those seen within tests with NB (Fig.…”

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confidence: 53%

“…We next studied how B. bacteriovorus HD100 responds to S. aureus biofilms by sequencing the total cellular RNA. As shown in Figure 2a, the transcriptomic responses during the exposure are highly reminiscent of those seen both during intraperiplasmic (IP) growth [17] and when B. bacteriovorus HD100 was incubated in nutrient broth (NB) [18]. One striking difference between the S aureus biofilminduced transcriptomic responses and the other conditions was EggNOG (Evolutionary genealogy of genes: Nonsupervised Orthologous Groups) category "N" (Fig.…”

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confidence: 87%

“…The differences between the three studies are thought to be due to the nature of the predator and its environments; the release of amino acids from the S. aureus biofilm through the induced proteolytic activities may act as a chemoattractant for swimming predator cells, as demonstrated by LaMarre et al [19] in their study with Bacteriovorax stolpii UKi2. In contrast, IP growth requires little or no movement while the media used by Dwidar et al [18] was homogeneous, precluding the need for the flagella or chemotactic responses. Likewise, the predators exposed to the S. aureus biofilms tended to have fewer EggNOG category "D" genes upregulated than the other published conditions.…”

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confidence: 99%

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Bdellovibrio bacteriovorus HD100, a predator of Gram-negative bacteria, benefits energetically from Staphylococcus aureus biofilms without predation

Dwidar

Mitchell

2018

The ISME Journal

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Bdellovibrio bacteriovorus HD100 is a predatory bacterium which lives by invading the periplasm of Gram-negative bacteria and consuming them from within. Although B. bacteriovorus HD100 attacks only Gram-negative bacterial strains, our work here shows attack-phase predatory cells also benefit from interacting with Gram-positive biofilms. Using Staphylococcus aureus biofilms, we show this predator degrades the biofilm matrix, obtains nutrients and uses these to produce and secrete proteolytic enzymes to continue this process. When exposed to S. aureus biofilms, the transcriptome of B. bacteriovorus HD100 was analogous to that seen when present intraperiplasmically, suggesting it is responding similarly as when in a prey. Moreover, two of the induced proteases (Bd2269 and Bd2692) were purified and their activities against S. aureus biofilms verified. In addition, B. bacteriovorus HD100 gained several clear benefits from its interactions with S. aureus biofilms, including increased ATP pools and improved downstream predatory activities when provided prey.

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confidence: 53%

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confidence: 87%

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confidence: 99%

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Bdellovibrio bacteriovorus HD100, a predator of Gram-negative bacteria, benefits energetically from Staphylococcus aureus biofilms without predation

Dwidar

Mitchell

2018

The ISME Journal

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“…To examine the impact of the treatment by predatory bacteria or violacein, the bacterial culture were prepared by centrifuging with 2,200 × g for 10 min (5430 R, Eppendorf, USA) and resuspended in HEPES buffer (pH 7.2) to an optical density (OD) of 1.0 at 600 nm wavelength. B. bacteriovorus HD100 was cultured as described previously 33,34 .…”

Section: Methodsmentioning

confidence: 99%

1114 - Combined application of bacterial predation and violacein to kill polymicrobial pathogenic communities

Im¹

2018

Preprint

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Violacein is a bisindole antibiotic that is effective against Gram-positive bacteria while the bacterial predator, Bdellovibrio bacteriovorus HD100, predates on Gram-negative strains. In this study, we evaluated the use of both together against multidrug resistant pathogens. The two antibacterial agents did not antagonize the activity of the other. For example, treatment of Staphylococcus aureus with violacein reduced its viability by more than 2,000-fold with or without B. bacteriovorus addition. Likewise, predation of Acinetobacter baumannii reduced the viability of this pathogen by more than 13,000-fold, regardless if violacein was present or not. When used individually against mixed bacterial cultures containing both Gram-positive and Gram-negative strains, violacein and B. bacteriovorus HD100 were effective against only their respective strains. The combined application of both violacein and B. bacteriovorus HD100, however, reduced the total pathogen numbers by as much as 84,500-fold. Their combined effectiveness was also demonstrated using a 4-species culture containing S. aureus, A. baumannii, Bacillus cereus and Klebsiella pneumoniae. When used alone, violacein and bacterial predation reduced the total population by only 19% and 68%, respectively. In conjunction with each other, the pathogen viability was reduced by 2,965-fold (99.98%), illustrating the prospective use of these two antimicrobials together against mixed species populations. Within nature, bacteria are found primarily within polymicrobial communities. This is also true of infections, which may include both pathogens and commensal microbes 1,2. One benefit that bacteria within these communities gain is an increased resistance to antibiotics 3,4. Two reasons for this include the presence of resistant strains 5,6 , which can degrade the antibiotic, or because the other strains act as a "sink" for the antibiotic, diluting its impact on the susceptible populations 7. To overcome this, researchers have often resorted to using a combination of antibiotics 8-10. Antibiotic resistance on a single species level can be either intrinsic or acquired. Intrinsic resistance is a characteristic that is coded for in the genome of the strain, independent of antibiotic pressure and not a consequence of horizontal gene transfer. An example of intrinsic resistance includes the outer membrane in Gram-negative bacteria, which modulates the cell permeability and limits the entry of hydrophobic antibiotics 11. Lacking an outer membrane, Gram-positive strains are generally less protected and antibiotics may enter these bacteria more easily 12. The result is that Gram-negative bacteria are less susceptible to many antibiotics that are effective against Gram-positive pathogens. A case in point is the bisindole antibiotic violacein, which is produced by a number of bacterial species 13 , including strains of Chromobacterium 14,15 , Janthinobacterium 16 , Collimonas 17 and Duganella 18. As an antibiotic, violacein is primarily active against Gram-positive strains 15,18-2...

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“…The predatory bacterial strains were likewise grown as previously reported (Stolp and Starr, 1963;Im et al, 2014;Dwidar et al, 2017). Briefly, each was streaked into double layer agar plates.…”

Section: Bacterial Strains and Their Growthmentioning

confidence: 99%

Viscosity has dichotomous effects onBdellovibrio bacteriovorusHD100 predation

Kwon

Cho

et al. 2019

Environmental Microbiology

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Summary 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).

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Attack-Phase Bdellovibrio bacteriovorus Responses to Extracellular Nutrients Are Analogous to Those Seen During Late Intraperiplasmic Growth

Cited by 23 publications

References 39 publications

Bdellovibrio bacteriovorus HD100, a predator of Gram-negative bacteria, benefits energetically from Staphylococcus aureus biofilms without predation

Bdellovibrio bacteriovorus HD100, a predator of Gram-negative bacteria, benefits energetically from Staphylococcus aureus biofilms without predation

1114 - Combined application of bacterial predation and violacein to kill polymicrobial pathogenic communities

Viscosity has dichotomous effects onBdellovibrio bacteriovorusHD100 predation

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