linda - biofilm and quorum sensing Flashcards
(30 cards)
Biofilm Basics
What is a biofilm?
A community of microorganisms attached to a surface and surrounded by a self-made extracellular matrix (ECM or EPS).
Biofilm Basics
What does EPS stand for and what does it consist of?
Extracellular Polymeric Substances; includes polysaccharides, proteins, lipids, and extracellular DNA (eDNA).
Biofilm Basics
Are biofilms just clusters of microbes?
No, they are highly organized, resilient communities with complex architecture and communication.
Biofilm Formation Stages
What is the first step in biofilm formation?
Attachment of planktonic cells to a surface.
Biofilm Formation Stages
Is initial attachment of microbes reversible?
Yes, initially it’s reversible; it becomes irreversible if conditions are favorable.
Biofilm Formation Stages
Name three factors that influence microbial attachment.
Surface properties, microbial adhesins (e.g., pili, fimbriae), and environmental signals (e.g., pH, nutrients).
Biofilm Formation Stages
What happens during Maturation I of biofilm development?
Cells begin dividing, EPS is produced, and initial biofilm structure forms.
Biofilm Formation Stages
What role does EPS play in biofilm formation?
Anchors cells, traps nutrients, and protects against environmental stress.
Biofilm Formation Stages
What begins to occur during early biofilm maturation?
Quorum sensing starts, enabling microbial communication.
Biofilm Formation Stages
What defines Maturation II of biofilm development?
Formation of microcolonies, 3D architecture, and water channels.
Biofilm Formation Stages
Why are water channels important in biofilms?
They allow for nutrient and waste exchange.
Biofilm Formation Stages
How does metabolic activity differ within a mature biofilm?
Outer layers may be aerobic and active; inner regions can be anaerobic and dormant.
Biofilm Formation Stages
What is the final stage of biofilm development?
Dispersion
Biofilm Formation Stages
What triggers biofilm dispersion?
Environmental stress, quorum sensing signals, or nutrient limitation.
Biofilm Formation Stages
How can dispersion occur?
Passively (e.g., shear forces) or actively (microbially regulated).
Biofilm Formation Stages
Why is biofilm dispersion important?
It enables spread to new surfaces and contributes to recurrent infections.
Biofilm Characteristics
Are biofilms usually monomicrobial or polymicrobial?
Polymicrobial—most include multiple species that interact within the community.
Biofilm Characteristics
How do polymicrobial biofilms impact clinical infections?
They are more complex and harder to treat due to complementary resistance.
Biofilm Characteristics
How much more resistant are biofilm microbes compared to planktonic ones?
Up to 1,000 times more resistant to antibiotics.
Biofilm Characteristics
What makes biofilms resistant to antibiotics?
ECM barrier, dormant cells, altered gene expression (e.g., efflux pumps).
Biofilm Characteristics
How do biofilms evade the immune system?
Phagocytes can’t penetrate ECM, leading to chronic inflammation without clearing the infection.
Biofilm Characteristics
What creates diverse microenvironments within biofilms?
Gradients of oxygen and nutrients.
Quorum Sensing (QS)
What is quorum sensing (QS)?
Chemical communication that allows microbes to coordinate group behaviors based on population density.
Gram-Positive Bacteria QS
What molecules are used for QS in Gram-positive bacteria?
Autoinducing peptides (AIPs).
