Luria Bertani (LB) + Amp and Tet

• 1. To prepare solid medium, mix 10 g of tryptone, 5 g of yeast extract, 10 g of NaCl, and 15 g of agar, and bring to 1 L with H₂O. (To prepare liquid medium, combine all ingredients except agar.)

• 2. Autoclave for 30 min.

• 3. Let cool for 1 h in a 55°C water bath.

• 4. Add 2 mL of 50 mg/mL ampicillin and 2 mL of 5 mg/mL tetracycline.

• 5. While the agar-containing medium is still warm, pour a thin layer (∼0.5 cm) into each Petri dish and let cool to solidify.

• 6. Store dishes or liquid medium at 4°C for up to 1 mo.

• © 2014 Cold Spring Harbor Laboratory Press