NZM Growth Agar

Principle and Interpretation

NZM Growth Agar is used for incubating Escherichia coli competent cells immediately after transformation to allow expression of transferred resistance genes before exposing cells to selective conditions. This medium was developed by Blattner and colleagues as a rich medium for the propagation of bacteriophages which infects its cell host, E. coli for replication (1). Cells grow very fast in this medium as it provides all the amino acids, vitamins and other metabolites required for cell growth (2). Casein enzymic hydrolysate provides nitrogen, amino acids, and carbon sources for the cells. Sodium chloride provides sodium ions for transport and osmotic balance and Magnesium sulfate is a source of magnesium ions required in a variety of enzymatic reactions, including DNA replication (3). NZM broth allows the cells to grow more rapidly as they do not have to synthesize nucleotide precursors and other factors required for growth. This medium contains agar as the solidifying agent for the growth of cells on plate.