Deoxyribonuclease test (DNAse) Principle, procedure

Deoxyribonuclease test (DNAse) is an important biochemical test for the conformation of staph aureus.

what is the Principle of Deoxyribonuclease test (DNAse)

Staph aureus has an enzyme called DEOXYRIBONULEASE. When DNA (deoxyribose nucleic acid) reacts with staph aureus, its enzyme( DEOXYRIBONULEASE ) hydrolyze the DNA.

which Reagents are use for DANse test ?

Basically, two reagents are used for the DNAse tests.

• 1. culture media containing deoxyribo nucleic acid.
• 2. 3.6% Hydrochloric acid (Hcl)

Deoxyribonuclease test (DNAse) procedure

1. Devide the culture media plate (containing Deoxyribo nucleic acid) into require number by marking under the culture plate.
2. Using sterile loop, pick the colony and inoculate the test organism.
3. Inoculate the positive and negative control on the same plate.
4. Incubate that plate over night at 37 C.
5. In the morning, cover the plate with hydrochloric acid.
6. Look for clearing around the colony after 5 minuts ( after adding Hydrochloric acid).

which bacteria are Deoxyribonuclease test (DNAse) positive?

Only Staph aureus bacteria have DNAse enzymes. Therefore it is Deoxyribonuclease test (DNAse) positive bacteria.

which bacteria are Deoxyribonuclease test (DNAse) negative?

Bacteria other than staph aureus are Deoxyribonuclease test (DNAse) negative, due to lack of DEOXYRIBONULEASE enzyme.

what is the importance of Deoxyribonuclease test (DNAse) ?

Deoxyribonuclease test (DNAse) is an important test for the distinguish of staph aureus and other strains of staph like epidermidis.