| Preparation
of Dehydrated Media |
General
directions for the preparation of dehydrated media are: |
|
| Weigh out the powdered media. The amount of powdered
media needed is indicated on the label of the media. Place a weigh boat
on the balance pan. Tare the balance. Slowly add the powder to the weigh
boat. Do not return any excess powder to the bottle. |
| If preparing 1 liter of media, you will need a 2 liter flask. Due to boiling
during autoclaving, the flask needs to be 2x the volume of the media being
prepared. |
|
| Add approximately 100 ml. of the 1000 ml. of distilled water to
the flask. Then slowly add the powdered media to the flask. The
weigh boat will fold to make a funnel. After adding all the powder, pour
the rest of the distilled water in the flask. |
| Place the flask on a hot plate and heat to just boiling
to dissolve powder. Remove flask from hot plate and loosely cap with foil
or cotton. |
 ® |
| Autoclave media at 121 C. at 15 psi for 15 minutes. |
|
| |
Open a bag of Petri dishes. Label in small letters the name or initials
of the media and the date. Do not open plates. Handle plates
aseptically. |
|
| |
Allow flask to cool. If you pour the plates while the
agar is too hot condensation will form on the lids. Water in the plates
will affect the growth of the bacteria. |
|
| |
Open Petri dishes like a clam shell. Do not lay lid down. Pour
agar into bottom of dish until bottom is covered. Allow the plates to
solidify. Invert and store in the refrigerator. Perform quality control
by placing two of your prepared plates in the incubator for 48 hours to
check for growth of contaminants. |
|
