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  1. culture
    growth after inocultion into or onto a medium
  2. mixed culture
    2 + species
  3. pure culture
    1 species, axenic
  4. subculture
    method to prepare a pure culture
  5. contaminants
    unwanted species
  6. growth media
    provides nutrients for microbial growth
  7. 3 properties of growth media
    • 1. physical state
    • 2. composition
    • 3. function
  8. physical state of growth media
    • liquid -broth, "nutrient broth"
    • semisolid - 0.3-0.5% agar, like yogurt
    • solid - 1-5% agar
  9. agar
    solidifying agent, derived from seaweed, solid at body temp
  10. chemical composition of growth media
    • defined (synthetic) media- all components known and quantified
    • complex- contains at least one component that is not chemically defined. ex: blood or extracts
  11. function of growth media
    • general purpose - grows a wide variety of MO's
    • enriched media - add ingredients like vitamins or amino acids to meet special nutritional needs
    • selective media - encourage some MO's while inhibit others. ex: 10% salt encourages staphylococcus to grow but discourages most others
    • differential media - grow multiple MO's, appear different. ex:  different color
  12. EMB agar
    a growth media that is both selective and differential.  It selects for gram - and differentiates lactose fermenters
  13. culture methods- The 5 I's
    • 1. inoculation - introduce a sample inoculum - small sample
    • 2. incubation - MO dependent
    • 3. isolation - seperate species, obtain a pure culture.  ex: streak, pour, or spread plates
    • 4. inspection - cultures
    • 5. identify - physical and chemical characteristics
  14. brightfield microscope
    specimen appears dark against a light background, magnificaiton is limited, good for fixed or stained
  15. darkfield microscopes
    specimen is lit up against a dark background, good living microbes
  16. phase contrast or differential microscope
    • interference contrast
    • different densities appear different colors.  no staining, living MO's
  17. fluorescent microscopes
    • diagnostic
    • Fab technique, fluorescent antibodies
  18. electron microscope
    replaces light with an electron beam, vacuum
  19. 2 types of electron microscopes
    • 1. scanning EM- looking at surface of specimen, 3D
    • 2. transmission EM - thin slices of specimen - 2D, cross section
  20. specimen preparation for a light microscope
    • 1. fixation - stick the cells to slide with either heat or chemical spray
    • 2. staining - apply dye.  simple stain has one dye.  differential stain has 2+ dyes to visualize different structures differentiates between types.
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2013-05-30 19:05:27

chapter three
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