DNAse agar: composition, preparation and uses




  • DNAse agar is a plate biochemical medium used to identify Staphylococcus aureus from other species.
  • It is most economically prepared from the dehydrated medium available commercially

Composition of DNAse agar:

  • Tryptose……………………….20 gm/ltr
  • Deoxyribonucleic acid…………2 gm/ltr
  • Sodium chloride………………..5 gm/ltr
  • Agar……………………………12 gm/ltr

Preparation of DNAse agar:

  • The medium is used at a concentration of 3.9 grams in every 100 ml of distilled water.
  • Prepare and sterilize as instructed by the manufacturer.
  • When the medium has cooled to 50-55°C, mix well and dispense in sterile petri dishes.
  • Date the medium and give it a batch number.

Quality control

  • pH of medium: this should be within the range pH7.1-7.5 at room temperature.
  • Test the medium each time it is used by inoculating on the same plate as the test organisms, Staphyloccal species known positive and negative DNAse activity.
  • Store the plates at 2-8°C in sealed plastic bags to prevent loss.

Use of DNAse agar:

  • Used to isolate Staphylococcus aureus from other species.

DNAse agar: composition, preparation and uses