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- Introduction
- Biofilms in the world
- Advantages of the biofilm way of life
- Biofilm development
- Freshwater biofilms
- Biofilms in the stream food web
- Importance of biofilms in stream ecology
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Biofilm development
Biofilm formation begins with an initial adhesion of bacteria on the substratum surface. They can form on almost every imaginable surface, rock, metal, plastic, glass, contact lenses, human tissues. This step is generally reversible at the beginning but becomes less reversible within minutes due to the progressive removal of water from in-between the interacting surfaces. Reversible attachment of pioneering bacteria to surfaces enables them to review the suitability of a particular micro-environment before committing to irreversible colonization of an unknown habitat. Bacterial motility is important for the initial attachment, allowing the cells to position themselves and contact the substratum.
Once the primary colonizers have adhered, secondary colonizers co-adhere with organisms already attached to the surface creating a multispecies biofilm. Growth of the biofilm involves an increase in microbial biomass plus the production of extracellular matrix.
Mature biofilms are highly complex both in terms of microbial diversity and three dimensional structure. Confocal scanning laser microscopy reveals a complex architecture of polysaccharide matrix with interconnecting channels and free water flow.
Once a mature biofilm has formed, it has to be able, by its internal cohesivity and adhesivity to the substratum surface, to withstand detachment forces. When the shear forces are too strong for the biofilm some parts can be washed away.
Notice: Coaggregation is defined as the adhesive interaction between two micro-organisms in suspension, while coadhesion is the interaction between a planktonic and an already adhering organism.
Sources : D. C. Sigee, 2005, Freshwater Microbiology, Wiley, p324-327
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Contact us
Stream Biofilm Research Group
School of Biological Sciences
The University of Auckland
3a Symonds Street
Auckland, New Zealand
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streambiofilm
gmail.com
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© Stream Biofilm Project, The University of Auckland 2008-2010
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