Lysogeny-Broth

This medium is for general growth of E. coli and other bacteria. There are several formulations differing in the amount of NaCl such as LB-Miller (10 g/L NaCl) and LB-Lennox (5 g/L NaCl). The higher salt concentrations were originally included for specific experiments with phages and is not necessary for growth of normal E. coli strains. Normal E. coli might grow best on Lennox (5 g/L NaCl). The low salt medium (modified Miller or Luria low salt) is useful for salt sensitive antibiotics such as Zeocin.

The standard medium we use is LB-Lennox.

LB from dry components

• 10 g/L Tryptone or Peptone
• 5 g/L yeast extract
• 5 g/L NaCl (Lennox), 10 g/L NaCl (Miller) or 0.5 g/L NaCl (modified Miller or Luria low salt)
• (20 g/L agar for solid medium) Mix components in a Schott flask and add a magnetic stirrer bar. Using the tap water in the lab, pH is usually around 7 so pH is not normally checked or set for this medium. The dry components can be mixed in a bottle and prepared using a microwave oven, see LBpowder.

LB-Luria (50 mL) from stock solutions

• 12.5 mL P40Y20 autoclaved Peptone/Yeast extract stock solution.
• 1 mL (Lennox), 2 mL (Miller) or 100 µL (modified Miller or Luria low salt) 25% w/v NaCl stock solution
• sterile water to 50 mL