LB
LB
Known as Lysogeny Broth (or sometimes, mistakenly, as Luria-Bertani medium), this rich medium is used routinely for growth of Escherichia coli. There are several variants on this medium, with differing amounts of NaCl; glucose may also be added, as in the original recipe (Bertani 1951).
Preparation
Per litre:
- 5g Yeast Extract
- 10g NaCl
- 10g Tryptone
- Up to 1L dH2O
Instructions
- Add 5g Yeast Extract, 10g NaCl and 10g Tryptone to a beaker
- Add 800ml dH2O and stir until all solids are fully suspended
- Make up to 1L with dH2O
- For solid media, add 4g agar per 200ml LB
- Autoclave
-NaCl LB
Per litre:
- 5g Yeast Extract
- 10g Tryptone
- Up to 1L dH2O
Uses
- Routine growth of Escherichia coli
- Checking for contamination in Streptomyces spore stocks or cultures
Notes
This is the Miller formulation, with 10g/L NaCl. Alternatively, 5g/L NaCl can be used (Lennox formulation) or no salt (-NaCl). The -NaCl (no salt) version of LB should be used when using salt sensitive antibiotics like hygromycin: for example, when cloning into pSS170. (Alternatively, DNA or DNB can be used for hygromycin selection.)
To make liquid LB medium, omit the agar and autoclave as above.
References
Bertani G. Studies on lysogenesis. I. The mode of phage liberation by lysogenic Escherichia coli. J Bacteriol. 1951;62(3):293–300.
