LB Lennox, a nutritionally rich medium, was developed by Lennox for the growth and maintenance of pure cultures of recombinant strains of E. coli. These strains are generally derived from E. coli K12 which are deficient in B vitamin production. LB Broth media formulations have been industry standards for the cultivation of Escherichia coli since the 1950's (1,2,3). These media have been widely used in molecular microbiology applications for the preparation of plasmid DNA and recombinant proteins (4,5). The media are nutrient-rich formulations which provide peptides and peptones, vitamins, and trace elements. The three formulations (Lennox, Miller and Luria) differ in the amount of sodium chloride, thus providing selection of the appropriate osmotic conditions for the particular bacterial strain and desired culture conditions. The low salt formulations, Lennox and Luria, are ideal for cultures requiring salt-sensitive antibiotics such as Zeocin?. Principles of the Procedure: Peptides an