Biofilms Final
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Transcript of Biofilms Final
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Biologically active matrix
of cells and extracellularproducts attached to a
solid surface
Microbial community
forming a slimy layer on
a surface
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Assemblage oforganisms that can beof different or same
species held togetherby extracellular
polymeric substancesor EPS which allows
them to developcomplex threedimensional, resilient,attached communities.
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Develop in all kinds of surfaces where
there is moisture and nutrients.
Although bacteria require aqueous
conditions for growth, they will adhere toany surface be it inorganic, living or
dead materials, or organic remains.
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Inert surfaces Community water
system pipes
Sulfide tailings andacid mine drainage
system
Industrial wastetreatment machines
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Living cell
surfaces
Plant root system
Ruminant digestivetract
Biliary system
Urinary tract
Teeth
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Able to exploitessential nutrientswhich accumulate inthe form of ions andmacromolecules atthe surface-waterinterface giving thema distinct ecologicaladvantage in an
otherwise nutritionallyunfavorableenvironment(Brown et al., 1981)
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Some examples are:
Staphylococcus aureus - catheters andsurgical implants
Streptococcus mutans - dental plaques
Candida albicans catheters, contactlenses
Coloechaete scutata, Choleochaete soluta- colony proliferation on the surface ofpolyethylene (plastics)
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Pseudomonasaeruginosa is acommon "pioneerbacteria whichcan adhere tostainless steel, evento electropolishedsurfaces, within 30seconds ofexposure.
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Heterogeneous structure which includes cellclusters, void spaces, water channels, endslime streamers that are affected by flow of
the fluid surrounding the biofilm
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Biofilm formation is affected by:
Surface material
Smoothness Flow velocity
Nutrient availability
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1. Surface conditioning
2. Adhesion of pioneer bacteria
3. Slime formation
4. Secondary colonizer
5. Fully functioning biofilm
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First, organic
molecules adhere
to the surfaceand they
neutralize the
surface charge
which may repelapproaching
bacteria.
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Planktonic (free-floating) bacteria firstattach themselves by
electrostaticattraction andphysical forces. Someof these cells will
permanently adhereto the surface withtheir extracellularorganic matrix.
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Extracellular polymersconsisting of charged andneutral polysaccharidegroups cement the cell and
act as an ion exchangesystem for trapping and
concentrating trace nutrients
Accumulation of nutrientspromotes reproduction of
pioneer cells. The daughtercells then produce their ownexopolymers, greatlyincreasing the volume of ion
exchange surface.
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The exopolymer websnares other types ofmicrobial cells throughphysical restraint andelectrostaticinteraction. Thesesecondary colonizersmetabolize wastes from
the primary colonizersas well as producetheir own waste whichother cells then use.
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Microbe-microbeinteraction Production of
metabolites byprimary colonizersmay promote orinhibit secondarycolonizers
The thicker thebiofilm, the higherthe occurrence ofanaerobiosis is
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Microbe-surface interaction
The rate of initial biofilm formation bybacterial adhesion is to a degreedependent on the chemical nature of thesurface
Type of bonding that exists between thebacteria and the substratum must be takeninto consideration.
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The process of communication of
bacteria to respond to local cell density
Regulates the secretion of stickyextracellular slime
Some species use quorum sensing to turn onslime production at high cell density; while
some turn it off.
Synchronize the expression of specialized
gene systems
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Less susceptible to antimicrobial agents
The matrix itself protects the cells from
coming into contact with the antimicrobialeffect of the agent.
e.g.
If the antimicrobial agents mode of action is
oxidizing,
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1: individual cells populate the surface. 2: extracellular polymeric substance
(EPS) is produced and attachment becomes irreversible.3 & 4: biofilm architecture develops and matures.
5: single cells are released from the biofilm.
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Release of bacteria from a biofilm may
be due to production of unattached
daughter cells through attached cellreplication. Other factors that promote
detachment are bulk fluid flow, lack of
oxygen, accumulation of toxic waste
products, biological grazing andpredator harvesting.
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Increased resistance toantibiotic andantibacterial substances
Resistance towards
disinfecting chlorines Metal corrosion due to
sulfate-reducingbacteria
Dental decay Food and water
contamination due tocolonization of pipes
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Used in waste watertreatment fordegradation ofsoluble organic or
nitrogenous waste Stabilize soil, either
by acting ascementing agent orflocculating soil
particles therebyimproving aerationand waterpercolation
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Ettinger, M. Advanced Healing.Com Journal. Retrieved 2
September 2010 fromhttp://www.advancedhealing.com/blog/2009/09/25/dr-
ettingers-biofilm-protocol-for-lyme-and-gut-pathogens/
Korber, D.R., J.R. Lawrence, H.M. Lappin-Scott, and J.W. Costerton.1995. Growth of microorganisms on surfaces. In: H.M. Lappin-Scott and J.W. Costerton (ed). Microbial biofilms. pp. 15-45.
Cambridge University Press, New York.
Lappin-Scott, H.M. and J.W. Costerton. 1995. Microbial biofilms. pp.
15-45. Cambridge University Press, New York.
Marsh, P.D. 1995. Dental plaque. In: H.M. Lappin-Scott and J.W.Costerton (ed). Microbial biofilms. pp. 15-45.Cambridge
University Press, New York.
McArthur, J.V. 2006. Microbial ecology: an evolutionary approach.pp. 257-261. Elsevier Inc., Burlington, MA, USA.