What is a biofilm ?
A surface associated microbial community comprised of living cells, extracellular matrix, and trapped materials
What are 7 features of biofilms?
- well organized and specialized
- High cell density and species diversity
- > 100µm in thickness
- Form gradients in pH, nutrients, etc.
- Exhibit cell to cell communication
- Have heterogenous physiology
- Resistant to stress and antibiotics
Do microbes maintain a unicellular life-style in biofilms?
No because in the natural environment, there is a level of cell to cell interaction between the microbes living in the biofilm
Why do microbes in nature tend to form biofilms?
Because it allows them to protect themselves
Also almost all microorganisms attach themselves to surfaces
Also allows them to secure constant nutritional levels
What are the 5 stages in the dynamic process of biofilm formation?
- adherance
- formation of micro colonies
- multiplication and social interactions
- Maturation
- Dispersal
What are the three mechanisms by which bacteria attach to a surface? (briefly)
- Non-specific adherence (reversible attachment)
- Specific adherence (irreversible attachment)
- Other mechanisms that promote attachment
What are 4 examples of non-specific or reversible attachment mechanisms?
- electrostatic attraction
- Hydrophobic interaction
- Ionic interaction
- van der Waal’s forces
What are 3 examples of specific/irreversible attachment
- Adhesion- receptor interactions
2. Co-aggregation and co-adhesion
What is co-aggregation?
bacteria coming together NOT on the biofilm
What is co-adhesion?
Bacteria binding together in the biofilm
- spatial organization of these interactions
What are 3 “other mechanisms” that promote attachment?
- synthesis of extracellular poly saccharides
- secreted proteins or peptide
- Released DNA
What does the microbiome include?
All the culturable and non-culturable organisms in a specific environment
What are 8 examples of negative interactions between bacteria in a biofilm
- competing for binding sites
- competing for nutrients
- antagonism
- metabolic inhibition
- contact dependent inhibition
- detachment
- increased diversity
- decreased productivity
What are 8 examples of positive interactions between bacteria in a biofilm
- co-adhesion
- metabolic cooperation
- nutritional synergy
- cross-feeding (food chains)
- mutualism / commensalism
- Quorum sensing cooperation
- increased productivity
- decreased diversity
what are 7 advantages to bacteria by living in biofilms?
- Immobilized microbial community
- Create micro-environments for ecological fitness
- Favor microbial social activities
- Favor metabolic co-operations
- Favor microbial adaptation to various stresses
- Protect the biofilm cells from lethal threats
- Trapping and storage of nutrients
What are 5 benefits generally from having biofilms?
- Clean the environment by trapping pollutants
- Help nutrient cycling in soil: benefit to agriculture
- Provide colonization resistance by invading pathogens
- Stimulate the development of host immune systems - 5. Generate essential nutrients such as vitamins
What are 4 negative impacts that biofilms have on the environment and industry ?
- water contamination and pipe plugging
- corrosion of materials
- Energy and heat loss
- food contamination, poisoning and spoiling
What are 7 negative impacts that biofilms can have on human health?
- contamination of hospitals/clinics
- medical device + implant infections
- Dental caries of periodontal disease
- potential cause for multiple antibiotic resistance (through horizontal gene transfer)
- microbial reservoirs, increase transmission of diseases
- difficult to eradicate biofilm infections
What are some challenges in controlling biofilm infections?
- lack of effective therapies to eradicate them
- increasing prevalence due to more implants and devices
- increasing antibiotic resistance
