Preparation of LB (Luria-Bertani) agar

 Luria-Bertani is the most preferred media to be used in phage research. This protocol describes how to make 1 L of Luria-Bertani agar (also known as LB agar) for the culturing of bacteria on plates. 

ready-made Luria Bertani Agar plates


Procedures/Steps

  1. Add 25g LB broth, Miller, and 15g agar (or 40g LB agar, Miller) per liter of water.
  2. Mix well by inverting the bottle several times until powder is dissolved.
  3. Mix well by inverting the bottle several times until powder is dissolved.
  4. Sterilize by autoclaving for 20 min at 15 psi (1.05 kg/cm2) on a liquid cycle.
  5. Following autoclave (while media are still liquid but cool enough to safely handle bottle) pour LB agar from the bottle into plates within a laminar flow hood. Allow ~50 mL per plate. The LB agar bottle must only be opened and the plates poured in a laminar flow hood to prevent contamination.
  6. Leave plates in a laminar hood until agar sets (~30 mins).
  7. When agar has set, replace the lid, invert plates, and store in an air-tight bag at 4 °C.
  8. Plates should be removed from 4 °C at least 1 h before use and placed in 30 °C incubators. To prevent condensation from the lid dropping onto the agar surface, wipe lids dry with Kim wipe and store plates inverted.

Reminder: only remove lid from LB agar plate while in a laminar flow hood to prevent contamination.

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