LB-Growth Medium w/o Sodium chloride is used in protein expression systems where Sodium chloride is used to induce protein. This media is extensively used for the maintenance and propagation of plasmid DNA and for the growth of the recombinant strains which contain protein expression vector. Tryptone provides all the required peptides and peptones. Yeast extract supplies all the essential vitamins, nucleotides, amino acids, carbohydrate and trace elements.