Effects of Different Antibiotics on Bacteria
Because of their small size, rapid rate of reproduction, and relatively simple structure, bacteria are excellent subjects for laboratory studies. This investigation will introduce you to techniques of microbiology that will be of use to you throughout your biological work. Procedure
1. Heat the test tubes of sterile agar medium in the water bath until the agar melts.
2. Remove the test tubes from the water bath. Let them cool enough to hold in your hand, but not so much that the agar becomes solid again. Perform the following transfer as quickly as possible. You must work rapidly so that the liquid agar will not cool and solidify before the transfer is completed.
3. Hold both a test tube of warm agar medium and the test tube containing the culture of bacteria in your left hand. Remove the cotton plugs and pass the mouth of each test tube through the burner flame twice. Flame the loop and cool it. Pick up a loopful of the bacterial culture and transfer it to the warm agar in the second test tube. Shake the loop in the liquid a few times and then remove the transfer loop. Flame the loop and the mouth of each test tube and replace the cotton plugs.
4. Roll the test tube of warm agar between the palms of your hands ti mix the bacteria with the agar. Remove the cotton plug and flame the mouth of the test tube. Lift the cover of the sterile petri dish at an angle of slightly more than 45 degrees. Keep the lifted cover directly over the bottom half to the petri dish to avoid contamination as much as possible. Pour the agar into the bottom half of the dish. Be certain that the mouth of the test tube does not touch either half of the petri dish. Remove the test tube and lower the cover. Move the covered petri dish gently along the table top in a figure-eight pattern to distribute the agar evenly. Allow the agar to cool until it becomes firm.
5. Remove the forceps from the 70% alcohol and pass the tips very quickly...
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