Serial-Dilution Technique

Another technique we learned today in lab is the serial-dilution technique.
It is used to tell us how many live bacteria are in a sample

You dilute the broth into 1:10^6 what it was, but since we don't have anything large enough to measure that we use this technique instead.

-Start with your 1mL of bacteria broth from the test tube.
-Find six more sterile test tubes and a few pipets.
-Take 9/10 mL of sterile broth into each of the 6 sterile test tubes
-Line all of your test tubes up in a rack and number them to keep them in order
-Take 1/10mL of the original sample through a pipet and put it into test tube 1
-Give the test tube a flick to mix the solutions
-Then take 1/10 mL of the solution in 1 and put it into 2.
-Give the tube a flick
-Take 1/10 mL from 2 and put it into 3.
-Give 3 a flick
-Take 1/10 mL from 3 and put it into 4
-Give 4 a flick
-Take 1/10 mL from 4 and put it into 5
-Give 5 a flick
-Take 1/10 mL from 5 and put it into 6
-Give 6 a flick
-Find yourself 7 clean streak plates, a bunsen burner, a bottle of alcohol, and a glass hockey stick

- Label the plates to match the 7 test tubes
-Starting with tube 6 so that you can use the same pipet.
-Pipet 1/10 mL of each test tube onto their matching plate
-Use the glass hockey stick (cleaned with alcohol and fire) and spread the solution around
-Re-sterilize for each plate.
-Put the test tubes and the plates into the incubator and wait until next lab to see what you get.


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