Materials:

- LB agar plate

- LB media

- Tubes

Procedure:

Fill each tube in the dilution with 90 µl of LB.

Add 10 µl of the sample to the first tube and mix.

From the first tube, remove 10 µl and mix into second tube.

Repeat for the number of dilutions you wish to do (8 should be more than enough).

Take 10 µl from each dilution and spot it on to the agar plate.

Allow droplet to dry and incubate.

The first dilutions will contain a thick lawn of cells and the last dilutions will contain no cells. There should be one drop which contains countable single colonies. From this, you can calculate the number of cells in the original sample. For example, if there 4 colonies on dilution 5, there are 4E4 cells/µl.