Aesculin hydrolysis test principle, procedure for streptococci

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.

The 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

  • Enterococci
  • Anaerobic cocci
  • Streptococcus porcinous
  • S. uberis
  • S.Suis
  • S.Sanguis
  • S.Bovis
  • S.Eequinus
  • S.Mutans
  • S.Salivarius
  • Listeria

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?

The following bacterias show aesculin hydrolysis test positive.
Anaerobic cocci
Streptococcus porcinous
S. uberis

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