Arginine is an amino acid that builds up protein. Arginine is hydrolyzed by some bacteria, which release an enzyme called arginine dihydrolase.
It is characteristic of certain enterobacteria.
Arginine dihydrolase test procedure
There are two types of procedures.
Following are the steps in procedure 1.
- Inoculate 5 ml arginine broth.
- Incubate for 24 hours at 37 C.
- Add 0.25 ml of Nessler’s reagent.
- NOTE: Brown color indicates Arginine dihydrolase test positive.
In the case of streptococci, 0.5 ml of culture to 4.5 ml distilled water, shake, and add 0.25 ml of Nessler’s reagents.
- Stab-inoculate into the arginine agar and pipette a layer of sterile liquid paraffin (1 cm depth) onto the surface.
- Incubate at 37 C.
- The red color is a positive sign of the arginine test.
Reagents and media preparation for Arginine hydrolysis test
- Nessler’s reagent
- Arginine brothpreparation– Following are the components of arginine broth.
- Peptone water – 5 g
- Yeast extract – 5 g
- K2HPO4 – 2 g
- Glucose – 0.5 g
- Arginine monohydrochloride- 3 g
- Distilled water – 1000 ml
- Procedure: Dissolve by heating and adjusting PH to 7.0, boil, filter, and sterilize at 115 C for 20 minutes.
- Arginine agar preparation– consists of the following reagents.
- Peptone water -1 g
- NaCl – 5 g
- K2PO4 – 0.3 g
- Phenol red 1 % aqueous solution – 1 ml
- L- arginine hydrochloride – 10 g
- Agar – 3 g
- Distell water – 1000 ml
- Procedure: Dissolve the media in the water, and adjust PH to 7.2. Distribute into the screw-capped bottle to a depth of 16 mm and sterilize at 121 C for 15 minutes.
Arginine dihydrolase test for positive/negative bacteria
Positive Bacteria: Enterococci Faecalis NCTC 8213
Negative Bacteria: Streptococcus Salivarus NCTC 8618 or ATCC 7073
What is the arginine dihydrolase test used for?
Arginine is an amino acid that builds protein. Dihydrolase is an enzyme that breaks arginine. Some bacteria have this enzyme. Therefore arginine dihydrolase test was used to identify that bacteria.
Which bacterias show arginine dihydrolase test positive?
Basically, two bacteria show arginine dihydrolase test positive.