DNase Test Agar

DNase Test Agar is used for the differentiation of microorganisms on the basis of deoxyribonuclease activity in a laboratory setting. DNase Test Agar is not intended for use in the diagnosis of disease or other conditions in humans.

In 1956, Weckman and Catlin showed a correlation between increased DNase activity of Staphylococcus aureus and positive coagulase activity. Their research suggested DNase activity could be used to identify potentially pathogenic staphylococci. DiSalvo confirmed their results by obtaining excellent correlation between coagulase and DNase activity of staphylococci isolated from clinical specimens. Jeffries, Holtman, and Guse incorporated DNA in agar to study DNase production by bacteria and fungi. Polymerized DNA precipitates in the presence of 1N HCl, creating an opaque medium. Organisms that degrade DNA produce a clear zone around an inoculum streak. Fusillo and Weiss studied calcium requirements of staphylococci for DNase production, and concluded additional calcium was unnecessary when a complete nutritive medium was used.


Formula Liter
Enzymatic Digest of Casein 15 g
Enzymatic Digest of Animal Tissue 5 g
Sodium Chloride 5 g
Deoxyribonucleic Acid 2 g
Agar 15 g

Final pH: 7.3 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.


  1. Suspend 42 g of the medium in one liter of purified water.
  2. Heat with frequent agitation and boil for one minute to completely dissolve the medium.
  3. Autoclave at 121°C for 15 minutes.

Order Details

Product # Product Description
7129A DNase Test Agar, 500 g
7129T DNase Test Agar, 5 kg