Sunday, 6 March 2016


2. Methods

2.1 Equipment List

We used:
  • Spreader  
  • E. Coli
  • Petri Dish
  • Test tube rack
  • Forceps
  • Agar Plate

2.2 Diagrams of experimental setup  

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Figure 1: Experimental setup used to detect the radioactive levels of the Americium-241
2.3 Procedures

  1. Label the agar plates with the usual 5 items. Also mark, using dots, where you will put the BLANK disk. b. Disks should not be placed near the edge of the plate
  2. Inoculate one plate with your first bacterium as follows:
  3. Using the Aseptic Technique , spread the E.coli using the Spreader evenly
  4. Place one blank disk onto the surface of the agar
     c. Carefully pick up your test disk with the forceps, and gently place it in the
       appropriate spot on the agar surface,
     d. To ensure that the disk is flat on the agar,gently push it down with the forceps      
     e.  Reheat the tips of the forceps as above to kill any bacteria.

  1. Repeat the procedure with the second antibiotic disk.
  2. Repeat the procedure with the BLANK disk.
  3. Repeat steps 1 – 6 on a new agar plate with your second bacterium.
  4. Wait until the surface of the plates has completely dried (it may help to leave the lid slightly open for 3 - 5 minutes).
  5. Incubate both plates at 37C
  6. Will be recording diameter of the zone of inhibition in mm (see the two figures below), and record your results in the Table on the next page. If there is no
  7. zone present, record your result as 0 mm.

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