Biofilm
A biofilm is a structured community of microorganisms — predominantly bacteria — that are attached to a surface and enclosed within a self-produced extracellular matrix of polysaccharides, proteins, and nucleic acids. Bacteria within biofilms exhibit markedly different gene expression from their planktonic (free-floating) counterparts and can be up to 1000 times more resistant to antibiotics and immune responses. Biofilms are clinically significant as causes of chronic infections (e.g., on medical implants and catheters) and are also exploited beneficially in wastewater treatment and bioremediation.
Stages of Biofilm Formation
| Stage | Description | Key Process | Reversibility |
|---|---|---|---|
| 1. Initial attachment | Planktonic cells adhere to surface | Van der Waals forces | Reversible |
| 2. Irreversible attachment | Stable adhesion via pili/fimbriae | Adhesin-receptor binding | Irreversible |
| 3. Early development | Microcolony formation begins | Cell division, EPS production | Irreversible |
| 4. Maturation | Three-dimensional structure forms | Quorum sensing signals | Irreversible |
| 5. Dispersal | Cells detach and colonise new sites | Enzymatic EPS degradation | Reversible |
Interactive Tools
NCBI – Biofilm Research Articles
Access peer-reviewed research on biofilm biology and clinical relevance.
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Related Terms
Quorum Sensing
Quorum sensing is a cell-density-dependent chemical communication system used by bacteria to coordinate gene expression across a population by producing, releasing, and detecting small signalling molecules called autoinducers (AIs). When the concentration of autoinducers exceeds a threshold — indicating that a quorum (sufficient population density) has been reached — bacteria collectively switch on genes controlling biofilm formation, virulence factor production, sporulation, and bioluminescence. Quorum sensing allows bacteria to act as a multicellular unit, and disrupting it is being investigated as a novel anti-virulence strategy to combat antibiotic-resistant pathogens.
Bacteria
Bacteria are single-celled prokaryotic microorganisms that lack a membrane-bound nucleus and reproduce primarily by binary fission. They are among the most abundant life forms on Earth, inhabiting nearly every environment including soil, water, and the human body. Bacteria play essential roles in nutrient cycling, decomposition, and digestion, and certain species cause infectious diseases while others are harnessed in biotechnology and food production.
Antibiotic Resistance
Antibiotic resistance is the ability of bacteria to survive and multiply in the presence of an antibiotic that would normally inhibit or kill them, arising through genetic mutations or acquisition of resistance genes via horizontal gene transfer. It develops because antibiotics exert selective pressure on bacterial populations, favouring the survival and proliferation of resistant strains. The World Health Organization (WHO) considers antibiotic resistance one of the greatest global public health threats, as it renders standard treatments ineffective and increases the risk of fatal infections.
From Greek "bios" (βίος) meaning "life" and Latin "film" meaning "thin membrane". The term was popularised by J. William Costerton in the 1970s–1980s, who described the structured communities of microorganisms attached to surfaces in natural and clinical environments.