1.Label20 Falcon tubes as following: Name, Peptone Concentration , and test tube number. there should be four test tubes for each of the following five concentrations: 0%, 1%, 2%, 3%, 5%. Each of the four test tubes for each concentration should have the following labels: blank, one, two, or three.

2.Pipette 5mL of each peptone concentration onto their four respective test tubes.

3.Add 100 µLof Halobacterium to every test tube if every peptone concentration except for the test tube labeled blank for each concetration. If using pre-inculum Halobacterium, use a toothpick and swipe a few cells from an agar plate, then drop the toothpick into the test tube.

4. incubate test tube for 48 hours in 37Celsicus and 220 rev/min (rpm) conditions. Record start time of incubation.

5. Removed tubes from the incubator after the 48 hour incubation period and add 1mL from each tube to an empty cuvette; for the ''blanks' add 1mL into two cuvettes, (the blanks will be used as the reference.)

6. Using the spectrophotometer, measure the cell density of concentration.

7. Record and plot data.

8. Clean up our lab space and lab materials.

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