What does DNase Agar contain?

What does DNase Agar contain?

DNase agar is a differential medium that tests the ability of an organism to produce an exoenzyme, called deoxyribonuclease or DNase, that hydrolyzes DNA. DNase agar contains nutrients for the bacteria, DNA, and methyl green as an indicator. Methyl green is a cation which binds to the negatively-charged DNA.

What is the composition of DNase Agar with methyl green?

The acid precipitates unhydrolyzed DNA making the medium opaque. Therefore, DNase producing colonies hydrolyze DNA and produce a clear zone around the growth. Pancreatic digest of casein (10 g), yeast extract (10 g), deoxyribonucleic acid (2 g), NaCl (5 g), agar (15 g), methyl green (0.5 g), pH 7.5.

What dye is used in DNase Agar?

dye methyl green
DNase agar is a nutrient medium with the dye methyl green present. It also contains DNA to serve as the target for the enzyme.

What is the substrate in a DNase test?

DNA is the substrate for DNase activity. DNase is an extracellular enzyme that breaks the DNA down into subunits composed of nucleotides. The depolymerization of the DNA may be detected by flooding the surface of the medium with 1N HCl and observing for clear zones around the medium surrounding the growth.

How do you make a DNase Agar?

Preparation of DNAse agar:

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

What is the principle of the DNase test?

Principle. The deoxyribonuclease (DNase) test detects the degradation of DNA by bacterial species that produce DNase. The DNase test may be performed on plate media and is available in some commercial tests, e.g., QuadFERM+.

How do you make a DNase agar?

What is the principle of DNase test?

Does Staphylococcus aureus produce DNase?

Deoxyribonuclease (DNase) is an enzyme that breaks down DNA. Certain species of bacteria have the ability to produce the DNase enzyme – Staphylococcus aureus, Staphylococcus intermedius, Staphylococcus hyicus, Group A Streptococcus, and Serratia marcescens.

What are 2 indicators that can be used in the DNase test?

Media Used DNase Test Agar Base is used for testing the production of the DNase enzyme. The medium can also be added with indicators like methyl green or toluidine blue O.

What do you need to know about DNase agar?

DNase agar is a differential medium that tests the ability of an organism to produce an exo-enzyme, called deoxyribonuclease. DNase are extracellular endonucleases that cleave DNA and release free nucleotides and phosphate. DNase agar contains nutrients for the bacteria, DNA, and mostly methyl green as an indicator.

How is DNase used to differentiate Staphylococcus aureus?

Used to differentiate Staphylococcus aureus which produces the enzyme deoxyribonuclease from other Staphylococci which do not produce DNase. Particularly useful if plasma is not available to perform coagulase test or when the result of coagulase tests are difficult to interpret.

Are there any bacteria that do not show up on DNase test?

Limitation of DNase Test. Some MRSA strains do not give positive DNase test result and some strains of the coagulase negative staphylococci such as Staphylococcus capitis may give weak reactions. Serratia and Moraxella species also produce deoxyribonuclease. 1N HCl is bactericidal for staphylococci.

How is the hydrolysis of DNA indicated by Agar?

The hydrolysis of DNA is indicated by the clearing of the agar after the addition of HCl (the oligonucleotides dissolve in acid causing a clear zone, but DNA salts are insoluble). When methyl green indicator is added, DNA combines with the methyl green to produce a green color.