ACETAMIDE BROTH (DOUBLE PACK)

Specifications

Ingredients: gms/lit.
Part A: Acetamide 10.00
Part B: Sodium chloride 5.00
Dipotassium hydrogen phosphate 1.39
Potassium dihydrogen phosphate 0.73
Magnesium sulphate 0.50
Phenol red 0.012
Final pH (at 25°C): 7.0 + 0.2

Instruction for use :
Suspend 7.63 grams of part B in 1000 ml distilled water. Add 10.0 grams of Part A. Heat if
necessary, to dissolve the medium completely. Dispense in 10ml amounts in tubes or as desired.
Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.

Principle:
The media contains inorganic salts and acetamide a sole carbon and nitrogen source. However very
few organisms growing in the medium metabolize acetamide by the process of deamination
(acrylamidase activity). This unique ability is useful in identification of various non-fermenting
gram-negative organisms. This ability is shown by Pseudomonas aeruginosa, Pseudomonas
aciovorans Group III (Achromobacter xylosoxidans) and Alcaligenes odorans. Acetamide
deamination leads to the liberation of ammonia, which thereby increases the pH of the medium,
leading to a subsequent colour change of the phenol red indicator from yellow orange to purplish
red. Some strains require upto seven days to exhibit a positive reaction as they deaminate
acrylamide slowly.
Phosphates in the media serve as buffering agents, Magnesium sulphate is a source of ions that
stimulate metabolism whereas Acetamide serves as the sole nitrogen and carbon source. Sodium
chloride maintains osmotic equilibrium. Phenol red is the pH indicator.