Conventional Bacterial Growth Media

BIO 101 has prepared most of the conventional bacterial growth media formulations into ready-to-autoclave mixtures that are available either in bulk powder form or powder packaged in capsules or pouches. In cases where pH adjustments are normally made after dissolving powders in water, biological buffers have been added so that pH adjustments are not necessary. Unless otherwise instructed, preparation of the media is done by adding capsules or powder mixtures to water and autoclaving without the need of pH adjustment.

L-Broth/LB-Medium were first described in the early days of phage genetics studies and are still widely used by the molecular biologist today. All of the formulations contained 10 g tryptone and 5 g yeast extract/liter(1-5). Most also included 0.1% sugar, which is no longer used in most cases. NaCl amounts varied between 0.5 g and 10 g. Low or no salt is used mainly when working with phage P1 where CaCl2 is used instead for efficient adsorption of the phage to the cell. For growth of plasmids, media with 5 or 10 g of salt works well. BIO 101 offers ̉L-BrothÓ as the low salt form, LB Medium as the form with 10 g NaCl, and LB-Medium, Lennox as the form with 5 g of NaCl. For working with phage lambda Mg++ is required for phage absorption, and if using LB Medium, it is best to add Mg++ because it cannot be relied upon for tryptone or yeast extract to contain enough to suffice. LB Medium for Lambda includes Mg++. BIO 101 has researched the role of growth media in plasmid and phage production and offers a number of speciality media (see pp 212-218) that will significantly increase yields of plasmid DNA or phage (pp 226).

References:

1. Lennox, E.S. (1955) Virology 1,190.
2. Luria, S.E. and Burrous, J.W. (1957) J. Bacteriol. 74,471.
3. Luria, S.E. et al. (1960) Virology 12,348.
4. Blattner, F., et al. (1977) Science 196,161.
5. Miller, J.H. (1972) Experiments in Molecular Genetics, Cold Spring Harbor Press, N.Y.