Growth media

Quantity per liter

Luria-Bertani (LB) medium (Sambrook et al., 1989):

• 0.5% (w/v) Select Yeast extract (Difco Laboratories, Detroit, MI) 5 g
• 1% Bacto-trypton 10 g
• 1% NaCl. 10 g

Adjust pH to 7,5 with NaOH, fill up to 1 l, and autoclave

M9 minimal medium (Ausubel et al., 1992):

• 2 g/l glucose
• 12.8 g/l Na₂HPO₄.7H₂O }
  3 g/l KH₂PO₄ }
  0.5 g/l NaCl } M9 salts
  1 g/l NH₄Cl }
• 1 mM MgSO₄
• 0.1 mM CaCl₂
• 0.5 mg/l vitamin B1

SOB medium (Dower et al., 1988)

• 2% Bacto-tryptone 20 g
• 0.5% Bacto-yeast extract 5 g
• 10 mM NaCl 10 ml van 1 M NaCl
• 2.5 mM KCl 25 ml van 100 mM KCl

Adjust to pH 6.8 - 7 with HCl, fill up to 900 ml water and autoclave

• 10 mM MgCl₂ } 100 ml van 100 mM MgCl₂
• 10 mM MgSO₄ pH 7.5 } + 100 mM MgSO₄ pH 7.5

• 1 l SOB medium
• 10 ml of a 2 M glucose solution
  or 20 ml of a 20% (w/v) glucose solution

When used in plates, 1.5% Select agar (Gibco BRL) is added to liquid medium before autoclaving.

Autoclaved medium is supplemented, as required, with

• chloramphenicol (25 µg/ml; Boehringer)
• ampicillin (100 µg/ml; Boehringer)
• 0.1 mM isopropyl-1-thio-b-d-galactopyranoside (IPTG; Promega, Madison, WI).

The optical density of cultures is measured with a Novaspec^®II Visible Spectrophotometer (Pharmacia LBK Biotechnology, Uppsala, Sweden) at 600 nm wavelength.