BacterTube™ Lowen Stein Jensen (LJ)

INTENDED USE

BacterTube™ Lowen Stein Jensen (LJ) is a selective medium used for culturing and isolating Mycobacterium species.

PRINCIPLES

BacterTube™ Lowen Stein Jensen (LJ) was developed by Lowenstein. He combined Congo red and malachite green to inhibit unwanted bacterial species. The current formulation is based on Jensen’s improvements, and this medium uses an egg-based glycerol suspension. Jensen’s version removes Congo red and uses a moderate concentration of malachite green to inhibit the growth of most microorganisms remaining after sample decontamination. This formulation also promotes the earliest growth of mycobacteria.
L-Asparagine and Potato Flour serve as sources of nitrogen and vitamins. Monopotassium Phosphate and Magnesium Sulfate enhance microbial growth while acting as a buffering system. Malachite green inhibits the growth of most microorganisms present on the sample while supporting the growth of Mycobacteria. Egg Suspension provides fatty acids and proteins required for mycobacteria metabolism. When warmed, albumin in the egg coagulates, thus providing a solid surface for culturing. Glycerol serves as a carbon source and facilitates the growth of human tuberculosis bacteria while being less favorable for bovine tuberculosis species.

Inoculate the sample into the Lowenstein-Jensen medium.
Incubate the medium in a CO2 environment at 35 – 37°C, avoiding light. Since the medium is in tube form, it should be incubated for one week with the cap loosened to allow CO2 circulation for initial growth. After one week, the caps should be tightened to prevent dehydration of the medium.
Check the medium within 5 to 7 days, then weekly for up to 8 weeks.
Examine the tubes under light to detect bacterial growth.
Examine the tubes under light and using a microscope to detect bacterial growth. Record and describe the colony morphology on the day of the first observed growth.
Refer to the appropriate references to record the colony count and support biochemical identification of acid-fast bacilli

RESULTS

After incubation for the required time, usually 18 – 24 hours, observe the colony growth within the medium.
To identify the isolated bacterium, further appropriate tests must be carried out.

BacterLab ensures the quality of each product batch by testing with ATCC reference strains.

Reference strains	Incubation conditions	Expected results
Mycobacterium avium ATCC 25291	35–37°C for 2–4 weeks under 5–10% CO2 conditions	Good growth, smooth colonies, non-pigmented
Mycobacterium gordonae ATCC 14470		Good growth, smooth colonies, yellow or orange in color
Mycobacterium kansasii ATCC 12478		Good growth, photogenic colonies, smooth to rough
Mycobacterium smegmatis ATCC 14468		Good growth, wrinkled colonies, cream-colored
M. tuberculosis H37RV ATCC 25618		Good growth, granular colonies, rough, with warty appearance, dry, and easily breakable

For 1 liter of medium