Jul 6, 2025
What is Biofilm
Biofilms are structured communities of microorganisms that attach to surfaces and embed themselves in a self-produced matrix of extracellular polymeric substances (EPS). These complex microbial ecosystems are remarkably resilient and are found in a wide range of natural, industrial, and clinical environments.
1. Defining Biofilm
At its core, a biofilm is:
“A sessile microbial community characterized by cells that are irreversibly attached to a surface or to each other, embedded in a matrix of EPS, and exhibiting an altered phenotype with respect to growth rate and gene transcription.”
— Costerton et al., 1995
The EPS matrix—primarily composed of polysaccharides, proteins, and nucleic acids—acts as a protective barrier and structural scaffold, making biofilms highly resistant to external stresses.
2. Microbial Composition
Biofilms are not single-species colonies. In most cases, they are multi-species consortia that include:
- Bacteria (e.g., Pseudomonas aeruginosa, Staphylococcus aureus)
- Fungi (e.g., Candida albicans)
- Algae
- Protozoa
These organisms communicate using chemical signaling (quorum sensing) and coordinate their behavior for survival and adaptation.
3. The Biofilm Life Cycle
Biofilm formation is a dynamic process that occurs in several stages:
Attachment: Free-floating (planktonic) microbes adhere weakly to a surface.
Microcolony: Cells produce EPS and anchor firmly to the surface.
Early biofilm: Beginning growth stage for a mature colony
Maturation: The biofilm grows in complexity and thickness, forming channels for nutrient and waste exchange.
Dispersion: Cells or clusters detach and return to the planktonic state to colonize new surfaces.
Each stage is regulated by environmental conditions and microbial communication.
4. Where Biofilm Forms
Biofilms can form on virtually any surface that is:
Moist
Nutrient-rich
Exposed over time
Common examples:
Teeth (dental plaque)
Medical implants (catheters, prosthetics)
Industrial pipelines
Water filtration membranes
Natural surfaces (rocks in rivers, plant roots)
5. Why Biofilms Matter
Biofilms are more than just a nuisance—they have significant impacts across sectors:
Medicine
Biofilm-associated infections are notoriously hard to treat and often recur.
Industry
Biofilms cause corrosion, clogging, and contamination in water systems and manufacturing equipment.
Agriculture
They affect irrigation efficiency and plant health.
Environment
They influence nutrient cycling and pollutant breakdown in aquatic systems.
Their resistance to antibiotics, disinfectants, and physical stress makes them especially problematic.
Key Facts
Biofilms can be up to 1,000 times more resistant to antibiotics than planktonic bacteria.
The EPS matrix can make up 50–90% of the biofilm’s total organic carbon.
Biofilms are responsible for ~80% of chronic infections, according to the NIH.
References
Costerton, J. W., Lewandowski, Z., Caldwell, D. E., Korber, D. R., & Lappin-Scott, H. M. (1995).
Microbial biofilms. Annual Review of Microbiology, 49(1), 711–745.
https://doi.org/10.1146/annurev.mi.49.100195.003431Hall-Stoodley, L., Costerton, J. W., & Stoodley, P. (2004).
Bacterial biofilms: From the natural environment to infectious diseases. Nature Reviews Microbiology, 2(2), 95–108.
https://doi.org/10.1038/nrmicro821Flemming, H.-C., & Wingender, J. (2010).
The biofilm matrix. Nature Reviews Microbiology, 8(9), 623–633.
https://doi.org/10.1038/nrmicro2415Donlan, R. M., & Costerton, J. W. (2002).
Biofilms: Survival mechanisms of clinically relevant microorganisms. Clinical Microbiology Reviews, 15(2), 167–193.
https://doi.org/10.1128/CMR.15.2.167-193.2002NIH (National Institutes of Health). (2002).
Research on microbial biofilms. NIH Publication No. 02–4902.
Archived SourceHoiby, N., Bjarnsholt, T., Givskov, M., Molin, S., & Ciofu, O. (2010).
Antibiotic resistance of bacterial biofilms. International Journal of Antimicrobial Agents, 35(4), 322–332.
https://doi.org/10.1016/j.ijantimicag.2009.12.011Branda, S. S., Vik, Å., Friedman, L., & Kolter, R. (2005).
Biofilms: The matrix revisited. Trends in Microbiology, 13(1), 20–26.
https://doi.org/10.1016/j.tim.2004.11.006O'Toole, G., Kaplan, H. B., & Kolter, R. (2000).
Biofilm formation as microbial development. Annual Review of Microbiology, 54, 49–79.
https://doi.org/10.1146/annurev.micro.54.1.49Fux, C. A., Costerton, J. W., Stewart, P. S., & Stoodley, P. (2005).
Survival strategies of infectious biofilms. Trends in Microbiology, 13(1), 34–40.
https://doi.org/10.1016/j.tim.2004.11.010Stoodley, P., Sauer, K., Davies, D. G., & Costerton, J. W. (2002).
Biofilms as complex differentiated communities. Annual Review of Microbiology, 56, 187–209.
https://doi.org/10.1146/annurev.micro.56.012302.160705
