LB Agar, Lennox Powder

Cat. no. C7660 CulGenex™ LB Agar, Lennox, 2L 70gm
Cat. no. C7661 CulGenex™ LB Agar, Lennox 500gm
Cat. no. C7662 CulGenex™ LB Agar, Lennox 2kg
Cat. no. C7663 CulGenex™ LB Agar, Lennox 10kg
Cat. no. C7669 CulGenex™ LB Agar, Lennox, 0.5L 6 pouches/pack


Hardy Diagnostics CulGenex™ LB Agar, Lennox is recommended for maintaining and cultivating recombinant strains of Escherichia coli for molecular analysis.

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.


LB, or "lysogeny broth", media formulations have been widely used for the cultivation of Escherichia coli since the 1950s, and have become an industry standard in molecular microbiology applications for the preparation of plasmid DNA and recombinant strains of E. coli . (3,5-8) In general, typical wild type strains of E. coli are capable of growth on minimal media. However, researchers have exploited auxotrophic mutations in strains used for molecular manipulations, making them dependent upon specific growth factors; one strain in particular, E. coli K-12, is deficient in vitamin B production and is incapable of growth on nutritionally deficient media.

The original recipe for LB medium was formulated by Giuseppe Bertani and published in 1951. (3) LB media have since been adapted by Miller, Lennox and Luria to contain differing concentrations of sodium chloride in order to provide the appropriate osmotic conditions for the strain of interest. LB Agar, Lennox contains half the sodium chloride concentration of LB Agar, Miller and ten times that found in Luria Agar, Miller. (3,5-8) Low salt formulations, such as those adapted by Lennox and Luria, are ideal for salt sensitive applications.

LB Agar, Lennox was adapted by E.S. Lennox in the mid 1950s and is a nutritionally rich medium designed to contain certain trace elements for the growth and maintenance of pure recombinant strains. CulGenex™ LB Agar, Lennox is based on this formulation and contains tryptone and yeast extract for amino acids, vitamins and essential minerals. The moderate amount of sodium chloride provides sodium ions for transport and helps maintain osmotic balance. Agar is the solidifying agent. If desired, glucose can be aseptically added during preparation to complete the medium described in full by Lennox. (5)


Gram weight per liter: 35.0gm/L
Tryptone 10.0gm
Sodium Chloride 5.0gm
Yeast Extract 5.0gm
Agar 15.0gm

Final pH 7.0 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original light beige.

Store the prepared culture media at 2-8ºC.



1. Suspend 35.0gm of the dehydrated culture media in one liter of distilled or deionized water. Stir to mix thoroughly.

2. Heat to boiling to dissolve completely.

3. Sterilize in the autoclave at 121ºC. for 15 minutes.

4. Cool to 45-50ºC. and aseptically dispense desired volume into sterile containers.


For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. G77.



Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.


The following organisms are routinely used for testing at Hardy Diagnostics:

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC ® 25922
A 18-24hr 35°C Aerobic Growth

User Quality Control

Physical Appearance

CulGenex™ LB Agar, Lennox powder should appear homogeneous, free-flowing, and light beige in color. The prepared media should appear slightly opalescent, and light amber in color.


1. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

2. Ausubel, F.M., R. Brent, R.E. Kingston, D.D. Moore, J.G. Seidman, J.A. Smith, and K. Struhl. 1994. Current Protocols in Molecular Biology . Vol. 1. Current Protocols, New York, N.Y.

3. Bertani, G. 1951. Studies on Lysogenesis. I. The Mode of Phage Liberation by Lysogenic Escherichia coli . J. Bacteriol. ; 62:293-300.

4. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

5. Lennox, E.S. 1955. Transduction of Linked Genetic Characteristics of the Host by Bacteriophage P1. Virology ; 1:190.

6. Luria, S.E., and J.W. Burrous. 1957. Hybridization Between Escherichia coli and Shigella . J. Bacteriol. ; 74:461-476.

7. Luria, S.E., J.N. Adams, and R.C. Ting. 1960. Transduction of Lactose-Utilizing Ability Among Strain of E. coli and S. dysenteriae and the Properties of the Transducing Phage Particles. Virology ; 12:348-390.

8. Miller, J.H. 1972. Experiments in Molecular Genetics . Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.

9. Sambrook and Russell. 2001. Molecular Cloning: A Laboratory Manual , 3rd ed. Cold Spring Harbor Laboratory. Cold Spring Harbor, N.Y.

ATCC is a registered trademark of the American Type Culture Collection.