For detection of deoxyribonuclease activity of microorganisms & identification of
pathogenic Staphylococci.
Specifications
PHYSICAL PARAMETERS
Description
A fine, free flowing, hygroscopic powder
Color
Light beige colored powder.
Solubility
Soluble in Distilled / de-ionized water at 50˚C
Color
Light yellow colored opalescent solution
pH
7.30±0.2 at 25˚C (42.00 g/ l)
Solidification
40˚C
Color
Light yellow colored opalescent gel or light blue with toluidine blue colored to slight opalescent g
Contents
Ingredients
Gram/Litre
Tryptone
15.00
Soya Peptone
5.00
Deoxyribose nucleic acid
2.00
Sodium chloride
5.00
Agar
15.00
pH at 25˚C
7.3 ±0.2
Directions
Dissolve 42.00 grams in 1000 ml distilled water. Boil to dissolve the medium
completely. Sterilize by autoclaving at 121 ˚C at 15 lbs for 15 minutes. Cool to room 40 to 45 ˚C
and distribute aseptically in petri plates with gentile shaking for equal distribution. Ensure
complete solidification and inoculate test sample aseptically.
The media can be fortified with 0.1g toluidine blue before sterilization for proper visualization.
DNase activity results in the production of a bright pink reaction due to the metachromatic
property of Toluidine blue. Some strains of Staphylococcus may be inhibited on DNase Test
Agar by the Toluidine blue. Further confirmatory tests for identification should be carried out.
