LB Broth (Lennox) (AS-1269) – Low Salt Medium for Molecular Biology

LB Broth (Lennox) is a nutritionally rich, non-selective liquid culture medium developed by Lennox in 1955 for the growth and maintenance of Escherichia coli in molecular biology laboratories. It is particularly suitable for recombinant E. coli K-12 derivatives requiring enriched media for optimal growth and plasmid maintenance.

Compared to the Miller formulation, LB Broth (Lennox) contains reduced sodium chloride (5.0 g/L vs 10.0 g/L), providing lower osmolarity (~170 mOsm/kg) that supports salt-sensitive strains, improved transformation efficiency, and stable plasmid propagation.

• Molecular Biology & Cloning: Routine E. coli cultivation, plasmid amplification, DNA transformation, protein expression (BL21)
• Transformation: Optimal ionic strength for competent cell protocols — improved transformation efficiency vs Miller
• Salt-Sensitive Strains: E. coli K-12 derivatives, phage lambda infection studies, osmotic stress applications
• Antibiotic Selection: Compatible with ampicillin, kanamycin, chloramphenicol, and tetracycline supplementation
• Teaching & General Use: Standard molecular biology instruction and general bacterial propagation

1. Dissolve 20.0 g of dehydrated medium in 1 litre of demineralised or purified water.
2. Mix or heat gently with agitation until fully dissolved.
3. Verify pH and adjust to 7.0 ± 0.2 if required (1 M NaOH or 1 M HCl).
4. Sterilise by autoclaving at 121 °C for 15 minutes.
5. Cool to room temperature before use or inoculation.
6. Add filter-sterilised antibiotics or supplements aseptically as required.

For LB Agar plates: add 15.0 g/L agar before autoclaving. Cool to 45–50 °C, add antibiotics aseptically, pour into sterile Petri dishes.

Total: 20.0 g/L  |  pH: 7.0 ± 0.2 at 25 °C  |  Osmolarity: ~170 mOsm/kg

Not classified as hazardous according to GHS criteria (AU WHS Regulations 2011). No hazard pictograms, signal word, or hazard statements required. Standard laboratory precautions apply.

Autoclave inoculated liquid cultures (121 °C, 30 min) before disposal. Dispose of unused dehydrated powder as general laboratory waste in accordance with local regulations.

Not classified as dangerous goods under ADG, IATA, or IMDG. No special transport requirements.