Predation, death, and survival in a biofilm: Bdellovibrio investigated by atomic force microscopy

Núñez, Megan E.; Martin, Michael R.; Chan, Phyllis; Spain, Eileen M.

doi:10.1016/j.colsurfb.2005.03.003

Cited by 64 publications

(38 citation statements)

References 33 publications

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“…For the liquid cultures, cocultures (also termed prey lysates), and cultures for preparing PFU and single-colony growth on agar, we followed the following protocols based on methods from previous publications (1,2,9).…”

Section: Methodsmentioning

confidence: 99%

“…Although for many years investigations of B. bacteriovorus concentrated on its predatory nature in planktonic environments, significant recent attention has been directed to predation in the more diverse and complex bacterial cell environments characteristic of biofilms (1,21,(26)(27)(28). In previous studies, our collaboration has explored interactions between wild-type Bdellovibrio predators and their prey at interfaces in model biofilm communities.…”

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confidence: 99%

“…When trapped atop a nutrient-poor flat surface with Escherichia coli prey cells, bdellovibrios multiply robustly and quickly devour their prey (29). In model E. coli biofilms submerged in liquid, B. bacteriovorus hunts vigorously, decimating or eradicating its prey in a single-component biofilm (1). However, B. bacteriovorus's effectiveness as a predator is inversely proportional to the nutrient concentration of the medium, leading us to wonder about the relative fitness for switching between predatory and HI Bdellovibrio or its variants in crowded, nutrient-rich environments.…”

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confidence: 99%

“…Upon recognition of a Gram-negative prey cell, B. bacteriovorus burrows into the prey's periplasm, forming a bdelloplast. The periplasmic bdellovibrio consumes its prey while elongating, septating, and then lysing the remains of the bdelloplast, allowing several new bdellovibrios to continue as hunters (1)(2)(3)(4). This process typically requires 3 to 4 h and takes place in a spherical bdelloplast, but under certain conditions, such as altered nutrient regimes (5) and downregulation of genes affecting motility (6), multiple bdelloplast morphologies and delayed bdelloplast lysis (5-8) have been documented.…”

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confidence: 99%

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Spatially Organized Films from Bdellovibrio bacteriovorus Prey Lysates

Ferguson

Núñez

Kim

et al. 2014

Appl Environ Microbiol

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Bdellovibrio bacteriovorus is a Gram-negative predator of other Gram-negative bacteria. Interestingly, Bdellovibrio bacteriovorus 109J cells grown in coculture with Escherichia coli ML-35 prey develop into a spatially organized two-dimensional film when located on a nutrient-rich surface. From deposition of 10 l of a routine cleared coculture of B. bacteriovorus and E. coli cells, the cells multiply into a macroscopic community and segregate into an inner, yellow circular region and an outer, off-white region. Fluorescence in situ hybridization and atomic force microscopy measurements confirm that the mature film is spatially organized into two morphologically distinct Bdellovibrio populations, with primarily small, vibroid cells in the center and a complex mixture of pleomorphic cells in the outer radii. The interior region cell population exhibits the hunting phenotype while the outer region cell subpopulation does not. Crowding and high nutrient availability with limited prey appear to favor diversification of the B. bacteriovorus population into two distinct, thriving subpopulations and may be beneficial to the persistence of B. bacteriovorus in biofilms.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Spatially Organized Films from Bdellovibrio bacteriovorus Prey Lysates

Ferguson

Núñez

Kim

et al. 2014

Appl Environ Microbiol

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“…Moreover, the contrast in the images originates primarily from the stain and not from the intrinsic density of target structures, limiting the resolution attainable by this approach. Atomic force microscopic studies have also been used to probe the bacterial surface, but detailed internal structures are not visible and the samples are also subjected to freeze-drying and staining (24,25). Cryo-EM and cryo-electron tomography are powerful alternatives for visualization of the global architecture of bacterial cells that have been preserved in their native state (4,19,29,39).…”

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Three-Dimensional Imaging of the Highly Bent Architecture of Bdellovibrio bacteriovorus by Using Cryo-Electron Tomography

2008

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Bdellovibrio bacteriovorus cells are small deltaproteobacterial cells that feed on other gram-negative bacteria, including human pathogens. Using cryo-electron tomography, we demonstrated that B. bacteriovorus cells are capable of substantial flexibility and local deformation of the outer and inner membranes without loss of cell integrity. These shape changes can occur in less than 2 min, and analysis of the internal architecture of highly bent cells showed that the overall distribution of molecular machines and the nucleoid is similar to that in moderately bent cells. B. bacteriovorus cells appear to contain an extensive internal network of short and long filamentous structures. We propose that rearrangements of these structures, in combination with the unique properties of the cell envelope, may underlie the remarkable ability of B. bacteriovorus cells to find and enter bacterial prey.Bacteria of the genus Bdellovibrio are highly motile predators that reside in diverse aquatic and terrestrial environments, as well as in the mammalian digestive tract (28; for a review, see reference 33). They prey on a variety of gram-negative bacteria, including several human pathogens, and could become an important tool in the probiotic treatment of disease (32). Within this genus, Bdellovibrio bacteriovorus is the species that has been best characterized biochemically and genetically (27). Investigations over the last four decades (20, 27, 33) have helped elucidate several aspects of the complex life cycle of this organism, which includes a free-swimming or attack phase and a prey-bound phase. Attack-phase B. bacteriovorus is propelled by a single long sheathed flagellum and is capable of attaining speeds up to 160 m/s. The predator swims and turns in apparently random directions until it finds and attaches to a prey cell. It then digests a region of the host cell outer membrane to make a small entry pore, penetrates into the host periplasm, and forms a growth chamber by reshaping and resealing the host outer membrane. The established parasite depletes the host cytoplasm and undergoes growth to form a single elongated spiral cell and segmented division to generate multiple progeny, and it develops a flagellum to gain motility. Ultimately, the chamber ruptures, releasing the nascent bacteria to reinitiate the life cycle.Conventional electron microscopic (EM) studies have provided valuable insights into morphological changes that occur during the life cycle of B. bacteriovorus (1, 2, 6, 7). However, room temperature EM imaging typically requires specimen preparation steps that include chemical fixation, removal of the aqueous phase by treatment with organic solvents, and embedding in plastic resins. These procedures can introduce artifacts, such as distortion of the cell shape, deterioration of membrane structures, and aggregation of soluble multiprotein complexes. Moreover, the contrast in the images originates primarily from the stain and not from the intrinsic density of target structures, limiting the resolution attainable...

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Have an Ion on It: The Life‐Cycle of Bdellovibrio bacteriovorus Viewed by Helium‐Ion Microscopy

2018

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Helium‐ion microscopy (HIM) has so far rarely been employed to image microbial interactions. Here, the visualization of the life‐cycle of the bacterial predator Bdellovibrio bacteriovorus HD100 with Escherichia coli and Pseudomonas putida, respectively, as prey is presented. The predator is brought in contact with prey and samples are taken at selected times. The system is monitored by phase‐contrast microscopy and HIM. For HIM imaging, a sample preparation protocol is established that preserves the structure of Bdellovibrio, prey, and bdelloplasts. The micrographs show the attachment of the predator to its prey, the evolution of bdelloplasts, their lysis, and the release of predator progeny. The combination of HIM with two more approaches allows for investigating predator–prey interactions from different angles: First, phase‐contrast micrographs provide quantitative information for the numbers of predator, prey, and bdelloplasts. Second, a numerical model solving the retarded differential equations that describe the system's time‐evolution is developed and fits the experimentally determined cell numbers. In conclusion, the high resolution, the large depth of focus, and surface sensitivity of HIM hold promise to expand future studies on so far neglected ecological interactions within the microbial food web, in particular in samples with pronounced topography such as bacterial biofilms.

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Predation, death, and survival in a biofilm: Bdellovibrio investigated by atomic force microscopy

Cited by 64 publications

References 33 publications

Spatially Organized Films from Bdellovibrio bacteriovorus Prey Lysates

Spatially Organized Films from Bdellovibrio bacteriovorus Prey Lysates

Three-Dimensional Imaging of the Highly Bent Architecture of Bdellovibrio bacteriovorus by Using Cryo-Electron Tomography

Have an Ion on It: The Life‐Cycle of Bdellovibrio bacteriovorus Viewed by Helium‐Ion Microscopy

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