DNase test agar with toluidine blue is primarily used in microbiology laboratories to detect the presence of deoxyribonuclease (DNase) enzyme activity in microorganisms, particularly bacteria. The agar serves as a growth medium, while toluidine blue acts as an indicator dye. When DNase-producing bacteria grow on the agar, they break down the DNA present in the medium, creating clear zones around the colonies. These zones become visible as the dye binds to the intact DNA, leaving the degraded areas unstained. This test is especially useful for identifying and differentiating species like Staphylococcus aureus, which is DNase-positive, from other staphylococci that lack this enzyme. It is a valuable tool in clinical diagnostics, food microbiology, and research for characterizing bacterial strains and assessing their enzymatic capabilities.