Materials

For 1 L of Media:

• 10g Tryptone
• 5g Yeast Extract
• 10g NaCl
• 10 g of Agar (for 1% Agar plates (w/v))
• 1 L ddH2O
• Sterile antibiotic stock solution (if required)

Directions

1. Pre-heat a water bath to 55C (optional). Add dry materials and water to a flask sufficiently large to minimize boil-over, such as using a 2L flask for 1L of media
2. Add a magnetic stir bar and stir the media.
3. Cover the top of the flask loosely with aluminum foil.
4. Autoclave the media for 30 minutes on a fluid cycle.
5. Remove media to 55C water bath or room temp to cool (if not using water bath, just make sure the timing is right so that you pour your plates before it starts to solidify). Once media has cooled sufficiently to around 55C, add antibiotics if required.
6. Obtain 2 sleeves of empty plates. 1 L of media will make about 40 plates. Using sterile technique, pour the media into the plates.
   • Cover the base of the plate, and then just a bit more after that.
   • Recap each plate upon pouring. If there are lots of bubbles in your plates (i.e., more than one or two on the edge), you can flame the plate using the small bunsen burner to eliminate bubbles. Another way to remove the fine bubbles that may be in your flask before pouring is to mist the inside of the flask with a 75% ethanol spray bottle.
7. Label the plates following these rules:
   • Red stripe - AMP
   • Blue stripe - KAN
   • Green stripe - CHLOR
   • Purple stripe - TET
8. Leave plates to dry and cool for a while (overnight even). Store the plates in their original bags - upside down, so that the gel is hanging downwards (this keeps condensation off the gel) in the cold room

Adapted from OpenWetWare