BacterPlate™ Dnase Agar

Ready-to-use medium on 90mm plates for detecting the deoxyribonuclease enzyme of microorganisms, particularly Staphylococci.
Code: 05030
Packaging: 10 plates/ box or as per customer request.
Storage Conditions: 2–8°C.
Transportation: Ambient temperature.
Shelf Life: 03 months from the date of manufacture.

INTENDED USE

BacterPlate™ Dnase Agar is recommended for the detection of deoxyribonuclease activity of bacteria and fungi, and especially for identification of pathogenic Staphylococci.
The packaging with semi-permeable Cellophane film helps balance the humidity of the environment during storage.

PRINCIPLES

BacterPlate™ Dnase Agar facilitates the detection of DNase activity through the hydrolysis of DNA incorporated in the medium. The process of DNA degradation is visualized using chemical indicators:
- Hydrolysis with HCl: DNA hydrolysis produces soluble oligonucleotides that dissolve in acid, while intact DNA remains as an insoluble salt. This creates a clear zone around DNase-positive colonies.
- Methyl Green Indicator: Methyl green binds to polymerized DNA, forming a stable green complex at pH 7.3. DNase activity disrupts the DNA structure, releasing methyl green and resulting in a colorless halo around positive colonies. The free methyl green naturally decolorizes at pH 7.3.
- Toluidine Blue O (TBO): TBO forms a complex with DNA that changes structure upon DNA hydrolysis, producing a bright pink coloration in the zone of hydrolysis.
These mechanisms allow for precise visualization and differentiation of DNase-positive microorganisms based on the enzymatic degradation of DNA.

Allow the agar plates to reach room temperature. Dry the plates in an incubator by slightly opening the lid.
Inoculate the plates by streaking microorganisms across the surface of the agar to observe thick colonies after 18 hours of incubation.
Inspect the plates for color changes inside or around the colonies if mannitol/ indicator or dye is added to the medium. In the absence of dye, fill the plates with 1N HCl and let them stand on the bench (lid side up) for a few minutes. Look for areas of fluorescence around the colonies.

RESULTS

1. Mannitol Indicator/pH:
Yellow color with yellow zone:	Mannitol +
Same color as the medium	Mannitol –
2 Toluidine blue:
Pink zone in blue medium	DNase +
No color zone	DNase –
3 Methyl green:
Nearly colorless zone	DNase +
No color zone	DNase –
4 Acid flood:
Clear zones clearly defined	DNase +
No clear zones	DNase –

BacterLab ensures the quality of each product batch by testing with ATCC reference strains.

Reference strains	Incubation Conditions	Expected results
S. aureus ATCC 25923	Incubate for 18 – 24 hours, 35 – 37°C	Good growth, clear bright zone
S. epidermidis ATCC 12228	Incubate for 18 – 24 hours, 35 – 37°C	Good growth, no clear zone