Microbiology Lecture 6
- Created by: emmawilliams
- Created on: 13-04-17 18:19
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Biofilms
- Biofilms are morphologically heterogeneous and multi-layered matrices commonly established by sessile bacteria able to attach to surfaces and also each other.
- Due to the energetic cost of adhering to and departing from a mature biofilm, the mechanism is strategically controlled.
- Biofilms are surface-attached communities of bacteria, encased in an extracellular matrix of secreted proteins, carbohydrates, and/or DNA, that assume phenotypes distinct from those of planktonic cells.
Formation of biofilms in nature
Biofilms offer their member cells several benefits:
The trapped cells can be exposed to toxic by-products, and also mass transfer limitations.
If external environmental conditions change, residents of a mature biofilm can be threatened. Under these circumstances bacteria respond by returning to their free-living lifestyle (planktonic) enabling them to disperse and re-colonise an alternative niche
Applications
- To purify water in water treatment plants.
- To break down chemicals often toxic.
- To produce biomolecules, including drugs.
Formation of biofilms in nature
- Over 90% of all bacteria live in biofilms.
- Biofilms are diverse from their formation on teeth as plaques and submerged rocks in a stream
Biofilms can be found:
- On humans
- Plants
- Animals
- Environmental, industrial or medical systems.
Biofilm phenotype
- A slower growth rate
- Increased antibiotic resistance
- Elevated frequency of lateral gene transfer
- Chemotaxis
- Motility
- Transport/uptake systems
- DNA release
- Polysaccharide production (EPS),
- P limitation,
- Cellulose
- Alginate
Polysaccharides
They impact on microbial virulence significantly. They determine biofilm architecture by protecting the cells from the host defenses and antimicrobials.
Bacteria have capsular…
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