Asculine is a glycoside and it is incorporated with a nutrient base a ferric salt. Aesculin hydrolysis means the breakdown of aesculin. This hydrolysis is indicated by a BROWN coloration.
It occurs due to the reaction of aglycone (6.7 Dihydroxycoumarin) with iron. Sometimes another chemical (SODIUM AZIDE) is added. It acts as a preservative.
Aesculin hydrolysis test is used to identify the enterococci, anaerobic cocci, streptococci, and others.
Aesculin hydrolysis test principle
Some organism hydrolyse aesculine. It results in the formation of a substance called AGLYCONE. It reacts with iron and forms a compound that is BROWN to BLACK in color.
Aesculin hydrolysis test procedure
Following are the steps in the aesculin test procedure.
- First, inoculate the aesculin broth or agar.
- Incubate that agar at 37 C temperature.
- Examine daily for up to 5 days.
- If you notice blackening, the result is positive.
Aesculin hydrolysis test positive bacteria / negative bacteria list
Aesculin hydrolysis Positive bacteria list
- Anaerobic cocci
- Streptococcus porcinous
- S. uberis
A. hydrolysis Negative bacteria list
All other streptococci
How to prepare aesculin hydrolysis agar?
Dissolve the masculine and iron salt in the peptone water and sterilize it at 115 C for 10 minutes.
How to prepare Aesculin cooked meat broth
Aesculin cooked meat broth accordingly, 1% aesculin is added before autoclave. Then 0.5% ml of an aqueous solution of ferric ammonium citrate solution is added.
Which bacterias show aesculin hydrolysis test positive?
Following bacterias show aesculin hydrolysis test positive.