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Quantifying the Effects of Antimicrobials on In vitro Biofilm Architecture using COMSTAT Software
Published on: December 14, 2020
Inoculation density and nutrient level determine the formation of mushroom-shaped structures in Pseudomonas
Azadeh Ghanbari1, Jaber Dehghany1, Timo Schwebs2
1Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.
Abstract:
Pseudomonas aeruginosa often colonises immunocompromised patients and the lungs of cystic fibrosis patients. It exhibits resistance to many antibiotics by forming biofilms, which makes it hard to eliminate. P. aeruginosa biofilms form mushroom-shaped structures under certain circumstances. Bacterial motility and the environment affect the eventual mushroom morphology. This study provides an agent-based model for the bacterial dynamics and interactions influencing bacterial biofilm shape. Cell motility in the model relies on recently published experimental data. Our simulations show colony formation by immotile cells. Motile cells escape from a single colony by nutrient chemotaxis and hence no mushroom shape develops. A high number density of non-motile colonies leads to migration of motile cells onto the top of the colonies and formation of mushroom-shaped structures. This model proposes that the formation of mushroom-shaped structures can be predicted by parameters at the time of bacteria inoculation. Depending on nutrient levels and the initial number density of stalks, mushroom-shaped structures only form in a restricted regime. This opens the possibility of early manipulation of spatial pattern formation in bacterial colonies, using environmental factors.
Insights
Pseudomonas aeruginosa biofilms form mushroom shapes when non-motile cells create colonies. Motile cells then migrate to form these structures, offering early intervention possibilities.
Area of Science:
- Microbiology
- Computational Biology
- Biophysics
Background:
- Pseudomonas aeruginosa frequently colonizes immunocompromised and cystic fibrosis patients.
- Antibiotic resistance in P. aeruginosa is often due to biofilm formation.
- Biofilm architecture, including mushroom-shaped structures, influences treatment efficacy.
Purpose of the Study:
- To develop an agent-based model simulating bacterial dynamics and interactions in P. aeruginosa biofilms.
- To investigate the influence of cell motility and environmental factors on biofilm morphology.
- To identify key parameters predicting the formation of mushroom-shaped structures.
Main Methods:
- Utilized an agent-based modeling approach.
- Incorporated experimental data on bacterial cell motility.
- Simulated bacterial growth, motility, and nutrient chemotaxis within a spatial environment.
Main Results:
- Immotile cells formed initial colonies.
- Motile cells escaped single colonies via chemotaxis, preventing mushroom formation.
- High densities of non-motile colonies facilitated motile cell aggregation and mushroom structure development.
- Mushroom formation was dependent on nutrient levels and initial stalk density.
Conclusions:
- Mushroom-shaped biofilm structures in P. aeruginosa are predictable based on initial inoculation parameters.
- Environmental factors and initial cell density critically influence spatial pattern formation.
- This model provides a framework for early manipulation of biofilm development.
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