DNase Test Agar is used to detect deoxyribonuclease activity of bacteria and fungi, particularly for the identification of Staphylococci. Methyl Green combines with the polymerized DNA substrate to form a stable, green complex. The DNA is depolymerized by DNase-producing bacteria, which exhibit a clear zone against the green background around the colony. Tryptose is the nitrogenous source. Sodium Chloride maintains the osmotic balance and Agar is the gelifying agent.