Lowenstein-Jensen Medium

Lowenstein-Jensen medium is based on the original formulation of Lowenstein that was subsequently modified by Jensen. It is used with fresh egg and glycerol for the isolation and presumptive identification of Mycobacterium spp., particularly Mycobacterium tuberculosis, from clinical samples.

L-Asparagine and Potato starch are sources of nitrogen and vitamins in the medium. Potassium hydrogen phosphate and magnesium sulphate enhance organism growth and act as buffers. Sodium citrate and malachite green are selective agents that have inhibitory effects on organisms other than the mycobacteria. Malachite green is also incorporated into the medium to provide a colour contrast between the colonies and the medium.

The required addition of egg emulsion provides the fatty acids and protein required for the metabolism of mycobacteria. Glycerol is also added which is said to enhance the growth of Mycobacterium tuberculosis however other strains of mycobacteria, particularly Mycobacterium bovis, may be inhibited by its presence.

Subsequently, sodium pyruvate (12.5 g/600ml) may be used as an alternative to glycerol to encourage the growth of Mycobacterium bovis.

Used with fresh egg and glycerol for the isolation and presumptive identification of Mycobacterium spp., particularly Mycobacterium tuberculosis, from clinical samples.

Additional Information

Shelf Life (days): 1095 days

Storage Temp (C): 10-30°C

Dehydrated Medium Appearance: Fine Powder

Prepared Medium Appearance: Firm Gel

Dehydrated Medium Colour: Blue / Green

Prepared Medium Colour: Pale Green

Dehydrated PH: 7.2±0.2

Prepared PH: 7.2±0.2

Recommended Incubation: Aerobically, enriched with 4-6% CO₂ at 35-37°C for 3 weeks

Formula*g/L

L-Asparagine: 3.6

Potassium di-hydrogen phosphate: 2.4

Magnesium sulphate: 0.24

Sodium citrate: 0.6

Malachite green: 0.4

Potato starch: 30.0

Total: 37.2

*Adjusted/supplemented as required to meet performance requirements