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2011-11-30 00:46:21

Microbial Ecosystems
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  1. What are microbial mats?
    Microbial mats are extremely think biofilms. They have existed for many years. Contain all the key nutrient cycles. Example: stromatolites
  2. What are biofilms?
    assemblages of bacterial cells attached to a surface and enclosed in an adhesive matrix secreted by the cells
  3. What is 'biogeochemical cycling'?
    Transformations of an element that are catalyzed by either biological or chemical agents, or both. Example: carbon cycle, nitrogen cycle, sulfur cycle, etc.
  4. What is bioremediation?
    It is the use of microorganism metabolism to remove pollutants. Example: composting, bioleaching, bioaugmentation
  5. What are 'micocolonies'?
    Clusters of a few cells that develop from a single colonizing cell.
  6. What is an ecosystem and habitat?
    Ecosystem is the sum total of all organisms and abiotic factors in a particular environment while a habitat is a portion of an ecosystem.
  7. What is Species richness? Species abundance?
    Species richness is the total number of different species present. Species abundance is the proportion of each species in an ecosystem.
  8. What are some differences between planktonic cells and biofilms?
    Planktonic cells are those bacteria living in fluid environments as opposed to biofilm cells that grow on a surface. Biofilm growth is almost always more extensive and diverse than the planktonic growth in the liquid that surrounds the surface.
  9. Difference between planktonic cells and biofilms:
    • 1. biofilm supports critical transport and transfer processes
    • 2. biofilm has greater tolerance; reason includes slower growth rates in biofilms, reduced penetration of antimicrobial substances through the extracellular matrix, and different patterns of gene expression.
  10. List the steps in biofilm formation.
    • 1. attachment
    • 2. colonization
    • attachment of more organisms
    • division
    • polysaccharide formation
    • communication (quorum sensing)
    • 3. development
    • 4. release of planktonic cells
  11. List the Four reasons for biofilm formation.
    • 1. Microbial self-defense that increases survival. Resist physics forces, phagocytosis by immune system cells, and penetration of antibiotics.
    • 2. Allows cells to live in a favorable niche
    • 3. Allows bacterial cells to live in close association with each other (cell-to-cell communication)
    • 4. "default" mode of growth compared to living in liquid media.
  12. List examples of biofilm formation.
    • 1. periodontal disease
    • 2. kidney stones
    • 3. Yellowstone National Park
    • 4. cooling or heating-water systems
  13. What is the 'rhizosphere'?
    It is the soil that surrounds the plant roots and receives plant secretions
  14. What are some cellular structures of biofilms?
    • 1. protein appendages (pili, flagella)
    • 2. cell surface proteins (e.g. Pseudomonas fluorescens)
    • 3. polysaccharides
  15. How could you control biofilm formation?
    • 1. antibiotics and antimicrobial agents
    • 2. durgs that prevent biofilm formation by interfering with intercellular communication
    • 3. limiting nutrients available to bacteria