LB medium

Bottle with LB medium and LB agar plate

LB (engl. L ysogeny b Roth) is a complex nutrient medium for cultivation of bacteria ( bacterial culture ). The composition was formulated in 1951 by Giuseppe Bertani. LB is often incorrectly referred to as Luria broth , Lennox broth or Luria-Bertani medium . LB is the most commonly used medium for growing Escherichia coli in microbiology .

composition

LB is a complex medium that is now prepared as an aqueous solution with the following ingredients:

Yeast extract (5 g / l)
Tryptone (10 g / l)
Sodium chloride (0.5–10 g / l)

The pH is adjusted to 7 with NaOH . Agar (15 g / l) is added for plate cultures. The medium is autoclaved at 121 ° C. for 20 minutes .

The original instructions from 1951 also contain 1 g / l glucose .

The formulations differ in the salt concentration, which is set according to the osmotic conditions of the bacterial strain and the desired culture conditions. The low salt formulations Lennox and Luria are ideal for crops that require salt-sensitive antibiotics such as: B. Zeocin .

Well-known formulations are:

LB-Miller (10 g / l NaCl)
LB-Lennox (5 g / l NaCl)
LB-Luria (0.5 g / l NaCl)

swell

^ Bertani, G. (1951): Studies on lysogenesis. I. The mode of phage liberation by lysogenic Escherichia coli . In: J. Bacteriol. Vol. 62, No. 3, pp. 293-300. PMID 14888646 , PMC 386127 (free full text).
^ Bertani, G. (2004): Lysogeny at mid-twentieth century: P1, P2, and other experimental systems . In: J. Bacteriol. Vol. 186, No. 3, pp. 595-600. PMID 14729683 , PMC 321500 (free full text).

[1] Bertani, G. (1951): Studies on lysogenesis. I. The mode of phage liberation by lysogenic Escherichia coli . In: J. Bacteriol. Vol. 62, No. 3, pp. 293-300. PMID 14888646 , PMC 386127 (free full text).

[2] Bertani, G. (2004): Lysogeny at mid-twentieth century: P1, P2, and other experimental systems . In: J. Bacteriol. Vol. 186, No. 3, pp. 595-600. PMID 14729683 , PMC 321500 (free full text).