PowerPoint Presentation On Biofilms and Quorum Sensing

PPT On Biofilms and Quorum Sensing

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1. Biofilms and Quorum Sensing

2. Biofilms
Biofilms are organised microbial systems consisting of cells associated with surfaces - Likely the most wide-spread mode of growth for bacteria in nature

3. Biofilms In the natural world most bacteria aggregate as biofilms -
they form when bacteria adhere to surfaces in aqueous environments and begin to excrete a polysaccharide that can anchor them to all kinds of material. The biofilm is held together and protected by the polysaccharide matrix. This matrix protects the cells within it and facilitates communication among them through biochemical signals. Bacteria living in a biofilm usually have significantly different properties from free-floating bacteria of the same species, as the dense and protected environment of the film allows them to cooperate and interact in various ways.

4. Biofilms
A biofilm can be formed by a single bacterial species, but more often biofilms consist of many species of bacteria, as well as fungi, algae, protozoa, debris and corrosion products. Once anchored to a surface, biofilm microorganisms carry out a variety of detrimental or beneficial reactions (by human standards), depending on the surrounding environmental conditions.

 5. Advantages for Bacteria
♦ Creation of habitable niches
♦ Protection against: - Physical forces (e.g. in flowing systems) - Phagocytosis by immune cells - Grazers (e.g. ciliates, amoeba) - Viruses
♦ Barrier against toxic substances
♦ Facilitates intercellular communication
♦ Close proximity of cells enables genetic exchange

6. Disadvantages for mankind:
♦ Immune system can not attack biofilms
♦ Antibiotics/antimicrobial agents fail
♦ Slow the flow of liquids or clog pipelines
♦ Accelerate corrosion of pipelines
♦ Risk for drinking water supply via pipes

7. Effects of Biofilms
Microbial biofilms on surfaces result in billions of dollars in losses yearly due to equipment damage, product contamination, energy losses and medical infections. Conventional methods of killing bacteria (such as antibiotics, and disinfection) are often ineffective with biofilm bacteria. The huge doses of antimicrobials required to rid systems of biofilm bacteria are environmentally undesirable  and medically impractical. Conversely, microbial processes at surfaces also offer opportunities for positive industrial and environmental effects, such as bioremediating hazardous waste sites, biofiltering industrial water, and forming biobarriers to protect soil and groundwater from contamination. 

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