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Home Protocols Recipes LB medium and LB agar-plates

LB medium and LB agar-plates

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LB-medium (1 L):
1. Dissolve 10 g tryptone, 5 g yeast extract, and 10 g NaCl in 950 mL deionized water.
2. Adjust the pH of the medium to 7.0 using 1N NaOH and bring volume up to 1 liter.
3. Autoclave on liquid cycle for 20 min at 15 psi. Allow solution to cool to 55°C, and add antibiotic if needed (50µg / mL of Amp or Kan).
4. Store at room temperature or +4°C.
LB agar-plates:
1. Prepare LB medium as above, but add 15 g/L agar before autoclaving.
2. After autoclaving, cool to approx. 55°C, add antibiotic (if needed), and pour into petridishes.
3. Let harden, then invert and store at +4°C in the dark.