Preparing 2% agar

1. Determine how many plates of agar you need for a trial

2. Determine the volume of agar of each plate; the table below indicates the approximate volume of agar needed for each size of plate

Size of petri dish                      Volume of agar (mL)

Small (5cm)                                                10

Medium (10cm)                                          20

Large (20cm)                                             70

3. Calculate the total volume of agar

4. Prepare the agar; the following directions explain how to prepare 100mL

a. Weight out 2.00g of non-nutrient agar powder into a weigh boat

b. Measure out 100mL of deionized water into a 100mL graduated cylinder

c. Get a 200mL Erlenmyer flask; refer to the table below to see what flask is needed for the appropriate amount of solution

Volumed of media to be autoclaved:              Use an Erlenmyer flask of:

100mL                                                                 250mL

200-300mL                                                          500mL

400-800mL                                                          1000mL

900-1000mL                                                        2000mL

d. Add all of the powder to the flask, followed by deionized water. Use a Sharpie and label tape to label the flask with your name

e. Fill out Autoclave Request Form. Place flask(s) and the form on the counter labeled as such. Make sure to carefully describe any specific aspects to the pouring of the agar.

Careful! Make sure the volume of the flask is twice the volume of the media being autoclaved!