Lysogeny Broth (LB) medium

Andreas Sagen

Published: 2023-01-06 DOI: 10.17504/protocols.io.ewov1o262lr2/v2

Abstract

Lysogeny broth (LB) is a nutritionally rich medium which is primarily used for the growth of bacteria[1]. The initialism is also commonly, albeit incorrectly, taken to mean Luria broth , Lennox broth , or Luria-Bertani medium . According to its creator Giuseppe Bertani, the abbreviation LB was actually intended to stand for lysogeny broth . The formula of the LB medium was

published in 1951 in the first paper of Bertani on lysogeny[2]. There are several common formulations of LB . Although they are different, they generally share a somewhat similar composition of ingredients used to promote growth, including the following: Peptides and casein peptones, Vitamins (including B vitamins), Trace elements (e.g. nitrogen, sulfur, magnesium) and Minerals.

Sodium ions for transport and osmotic balance are provided by sodium chloride (NaCl). Tryptone is used to provide essential amino acids such as peptides and peptones to the growing bacteria, while the yeast extract is used to provide a plethora of organic compounds helpful for bacterial growth. These compounds include vitamins and certain trace elements.

Before start

Prepare glassware by cleaning it, and ensure that scale is sufficiently calibrated

Steps

500 mL LB-Lennox (broth) medium

All compounds are measured using a high precision analytical scale from powdered compounds. Each compound is measured to within 1% of the target weight. All compounds are mixed in a Duran bottle

1.1.

Fill the bottle with 400mL double-distilled water

1.2.

Measure 5000mg Tryptone, 2500mg Yeast extract and 2500mg Sodium chloride

Powdered compounds:

1.3.

Add powdered solids into bottle, and use a magnetic mixer with a stir bar to mix for 0h 5m 0s

1.4.

Adjust pH while mixing to 6.7 using concentrated sodium hydroxide

1.5.

Add distilled water to a total of 500mL

1.6.

Autoclave liquid at 121°C for 0h 15m 0s

Note

Cool to 50°C and supplement with antibiotics as appropriate

500 mL LB-Lennox (agar) medium

All compounds are measured using a high precision analytical scale from powdered compounds. Each compound is measured to within 1% of the target weight. All compounds are mixed in a Duran bottle

2.1.

Fill the bottle with 400mL double-distilled water

2.2.

Measure 5000mg Tryptone, 2500mg Yeast extract, 2500mg Sodium chloride and 7500mg agar

Powdered compounds:

2.3.

Add powdered solids into bottle, and use a magnetic mixer with a stir bar to mix for 0h 5m 0s

2.4.

Adjust pH while mixing to 6.7 using concentrated sodium hydroxide

2.5.

Add distilled water to a total of 500 mL

2.6.