THE VIRTUAL EDGE: Lab 6 Cultivation of Bacteria II

Osmotic Pressure Procedure (NaCl)

    All four organisms will be tested for growth on media containing varying concentrations of NaCl: 0.5%, 7.5%, 20%, and 25%.

    Test Organisms:

    Saccharomyces cerevisiae
    Staphylococcus aureus
    Escherichia coli
    Halobacterium salinarium

  1. Collect 1 of each of the following plates:

    TSA + 0.5% NaCl
    TSA + 7.5% NaCl (=Mannitol Salt Agar, Red)
    TSA + 20% NaCl
    TSA + 25% NaCl

    On the bottom of the plates, use a marker to divide them into 4 quadrants as shown below.

  2. Label each quadrant with one of the test microorganisms. Also label the bottom of the plates with your initials, lab section, and the NaCl concentration of the plate.  There will be a total of 4 plates.
  3. Follow the procedure for Innoculating organisms into four quadrants.
  4. Repeat the procedure for all four organisms.  Streak them in their appropriately labeled quadrants.
  5. Repeat the inoculation procedure, as described in the video, for the remaining 3 plates. 
  6. Invert and incubate the plates at 37˚C for 24 - 48 hours.

Rachel Watson, M.S.
AG 5010
766-3524
Cell: 307-760-2942
rwatson@uwyo.edu

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