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Swarming and complex pattern formation in Paenibacillus vortex studied by imaging and tracking cells.

Ingham CJ, Ben Jacob E - BMC Microbiol. (2008)

Bottom Line: When swarming, P. vortex was found to be peritrichously flagellated.Mitomycin C treatment resulted in malcoordinated swarming and abortive side branch formation and a strong tendency by a subpopulation of the cells to form minimal rotating aggregates of only a few cells.This is the first detailed examination of the swarming behaviour of this bacterium at the cellular level.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medical Microbiology and Infection Control, Jeroen Bosch Hospital,'s-Hertogenbosh, The Netherlands. colin.ingham@wur.nl

ABSTRACT

Background: Swarming motility allows microorganisms to move rapidly over surfaces. The Gram-positive bacterium Paenibacillus vortex exhibits advanced cooperative motility on agar plates resulting in intricate colonial patterns with geometries that are highly sensitive to the environment. The cellular mechanisms that underpin the complex multicellular organization of such a simple organism are not well understood.

Results: Swarming by P. vortex was studied by real-time light microscopy, by in situ scanning electron microscopy and by tracking the spread of antibiotic-resistant cells within antibiotic-sensitive colonies. When swarming, P. vortex was found to be peritrichously flagellated. Swarming by the curved cells of P. vortex occurred on an extremely wide range of media and agar concentrations (0.3 to 2.2% w/v). At high agar concentrations (> 1% w/v) rotating colonies formed that could be detached from the main mass of cells by withdrawal of cells into the latter. On lower percentage agars, cells moved in an extended network composed of interconnected "snakes" with short-term collision avoidance and sensitivity to extracts from swarming cells. P. vortex formed single Petri dish-wide "supercolonies" with a colony-wide exchange of motile cells. Swarming cells were coupled by rapidly forming, reversible and non-rigid connections to form a loose raft, apparently connected via flagella. Inhibitors of swarming (p-Nitrophenylglycerol and Congo Red) were identified. Mitomycin C was used to trigger filamentation without inhibiting growth or swarming; this facilitated dissection of the detail of swarming. Mitomycin C treatment resulted in malcoordinated swarming and abortive side branch formation and a strong tendency by a subpopulation of the cells to form minimal rotating aggregates of only a few cells.

Conclusion: P. vortex creates complex macroscopic colonies within which there is considerable reflux and movement and interaction of cells. Cell shape, flagellation, the aversion of cell masses to fuse and temporary connections between proximate cells to form rafts were all features of the swarming and rotation of cell aggregates. Vigorous vortex formation was social, i.e. required > 1 cell. This is the first detailed examination of the swarming behaviour of this bacterium at the cellular level.

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Macroscopic pattern formation by P. vortex on MH agars. In all pictures the lighter areas are interconnected (moving) masses of cells and darker areas are uncolonized agar; all pictures taken after 18 h from Petri-dish-wide colonies. A. Swarming on 1.5% (w/v) agar MH plates from a point inoculation showing fractal pattern and (centrally) detached colonies. B. Swarming on 0.3% (w/v) agar MH plates after 28 h in which a network forms across the plate then elaborates. C. Detail of inoculation from a droplet on 0.3% agar with outgrowth at specific points from the central circular mass. D. Detail of pattern 30 mm from the center from the same plate as (C). Scale bar in (B) represents 2 cm when applied to panels (A) or (B) and 2 mm for (C) or (D).
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Figure 2: Macroscopic pattern formation by P. vortex on MH agars. In all pictures the lighter areas are interconnected (moving) masses of cells and darker areas are uncolonized agar; all pictures taken after 18 h from Petri-dish-wide colonies. A. Swarming on 1.5% (w/v) agar MH plates from a point inoculation showing fractal pattern and (centrally) detached colonies. B. Swarming on 0.3% (w/v) agar MH plates after 28 h in which a network forms across the plate then elaborates. C. Detail of inoculation from a droplet on 0.3% agar with outgrowth at specific points from the central circular mass. D. Detail of pattern 30 mm from the center from the same plate as (C). Scale bar in (B) represents 2 cm when applied to panels (A) or (B) and 2 mm for (C) or (D).

Mentions: Previously, colonial development of the P. vortex bacteria was studied during growth on Peptone plates and relatively hard surfaces (≥ 2% w/v agar). An example of representative colonial pattern in such setting is shown in Fig 1A. For more details see Refs [14,16,26,30,45-48]. These patterns are characterized by the formation of vortices – aggregates of tens to thousands of cells that rotate around a common center and move as a coherent unit. On softer surfaces (not shown here) the colonies are no longer composed of vortices and their shapes ("snakelike") was similar to that exhibited in Fig. 2A during growth on Mueller-Hinton (MH) plates.


Swarming and complex pattern formation in Paenibacillus vortex studied by imaging and tracking cells.

Ingham CJ, Ben Jacob E - BMC Microbiol. (2008)

Macroscopic pattern formation by P. vortex on MH agars. In all pictures the lighter areas are interconnected (moving) masses of cells and darker areas are uncolonized agar; all pictures taken after 18 h from Petri-dish-wide colonies. A. Swarming on 1.5% (w/v) agar MH plates from a point inoculation showing fractal pattern and (centrally) detached colonies. B. Swarming on 0.3% (w/v) agar MH plates after 28 h in which a network forms across the plate then elaborates. C. Detail of inoculation from a droplet on 0.3% agar with outgrowth at specific points from the central circular mass. D. Detail of pattern 30 mm from the center from the same plate as (C). Scale bar in (B) represents 2 cm when applied to panels (A) or (B) and 2 mm for (C) or (D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2268691&req=5

Figure 2: Macroscopic pattern formation by P. vortex on MH agars. In all pictures the lighter areas are interconnected (moving) masses of cells and darker areas are uncolonized agar; all pictures taken after 18 h from Petri-dish-wide colonies. A. Swarming on 1.5% (w/v) agar MH plates from a point inoculation showing fractal pattern and (centrally) detached colonies. B. Swarming on 0.3% (w/v) agar MH plates after 28 h in which a network forms across the plate then elaborates. C. Detail of inoculation from a droplet on 0.3% agar with outgrowth at specific points from the central circular mass. D. Detail of pattern 30 mm from the center from the same plate as (C). Scale bar in (B) represents 2 cm when applied to panels (A) or (B) and 2 mm for (C) or (D).
Mentions: Previously, colonial development of the P. vortex bacteria was studied during growth on Peptone plates and relatively hard surfaces (≥ 2% w/v agar). An example of representative colonial pattern in such setting is shown in Fig 1A. For more details see Refs [14,16,26,30,45-48]. These patterns are characterized by the formation of vortices – aggregates of tens to thousands of cells that rotate around a common center and move as a coherent unit. On softer surfaces (not shown here) the colonies are no longer composed of vortices and their shapes ("snakelike") was similar to that exhibited in Fig. 2A during growth on Mueller-Hinton (MH) plates.

Bottom Line: When swarming, P. vortex was found to be peritrichously flagellated.Mitomycin C treatment resulted in malcoordinated swarming and abortive side branch formation and a strong tendency by a subpopulation of the cells to form minimal rotating aggregates of only a few cells.This is the first detailed examination of the swarming behaviour of this bacterium at the cellular level.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medical Microbiology and Infection Control, Jeroen Bosch Hospital,'s-Hertogenbosh, The Netherlands. colin.ingham@wur.nl

ABSTRACT

Background: Swarming motility allows microorganisms to move rapidly over surfaces. The Gram-positive bacterium Paenibacillus vortex exhibits advanced cooperative motility on agar plates resulting in intricate colonial patterns with geometries that are highly sensitive to the environment. The cellular mechanisms that underpin the complex multicellular organization of such a simple organism are not well understood.

Results: Swarming by P. vortex was studied by real-time light microscopy, by in situ scanning electron microscopy and by tracking the spread of antibiotic-resistant cells within antibiotic-sensitive colonies. When swarming, P. vortex was found to be peritrichously flagellated. Swarming by the curved cells of P. vortex occurred on an extremely wide range of media and agar concentrations (0.3 to 2.2% w/v). At high agar concentrations (> 1% w/v) rotating colonies formed that could be detached from the main mass of cells by withdrawal of cells into the latter. On lower percentage agars, cells moved in an extended network composed of interconnected "snakes" with short-term collision avoidance and sensitivity to extracts from swarming cells. P. vortex formed single Petri dish-wide "supercolonies" with a colony-wide exchange of motile cells. Swarming cells were coupled by rapidly forming, reversible and non-rigid connections to form a loose raft, apparently connected via flagella. Inhibitors of swarming (p-Nitrophenylglycerol and Congo Red) were identified. Mitomycin C was used to trigger filamentation without inhibiting growth or swarming; this facilitated dissection of the detail of swarming. Mitomycin C treatment resulted in malcoordinated swarming and abortive side branch formation and a strong tendency by a subpopulation of the cells to form minimal rotating aggregates of only a few cells.

Conclusion: P. vortex creates complex macroscopic colonies within which there is considerable reflux and movement and interaction of cells. Cell shape, flagellation, the aversion of cell masses to fuse and temporary connections between proximate cells to form rafts were all features of the swarming and rotation of cell aggregates. Vigorous vortex formation was social, i.e. required > 1 cell. This is the first detailed examination of the swarming behaviour of this bacterium at the cellular level.

Show MeSH
Related in: MedlinePlus