Toluidine Blue DNA agar 100G

Toluidine Blue DNA agar is recommended for detection of thermostable deoxyribonuclease activity to establish speciation of S. aureus in contaminated food. The composition and performance criteria are in accordance with ISO 8870:2006(E) 83:2006(E). DNA in the medium acts a substrate for DNase activity. DNase producing organims depolymerizes the DNA resulting in the formation of a clear zone around colony. Toluidine blue produces visible bright rose-pink coloured reaction due to its metachromatic properties easying detection of DNase activity. Tris amino methane forms the buffering system. Sodium chloride and calcium chloride provides the ions and also maintains osmotic equilibrium. Staphylococcus aureus shows positive DNase activity while Staphylococcus epidermidis shows negative reaction.