AC Broth

Intended Use

AC Broth is used for cultivating a wide variety of microorganisms and for the sterility testing of turbid or viscous solutions and other materials not containing mercurial preservatives.

Summary and Explanation

AC Broth possesses growth-promoting properties for a wide variety of microorganisms. Christensen1 and Malin and Finn2 reported that AC Medium does not exhibit the toxicity
shown by media containing sodium thioglycollate. Several early studies reported on the wide variety of organisms able to grow on AC Medium.3-5 AC Broth is suitable for use in the detection of obligately aerobic contaminants in biologicals and other products. AC Broth is also useful in the isolation and cultivation of many common pathogenic and saprophytic aerobes.6 The medium can be used to test the sterility of biologicals and solutions that do not contain mercurial preservatives. Fluid Thioglycollate Medium should be employed for the sterility testing of solutions containing mercurial preservatives. 

User Quality Control

Identity Specifications
AC Broth
Dehydrated Appearance: Light tan, free-flowing, homogeneous.
Solution:                       3.4% solution, soluble in purified water. Solution
                                   is medium to dark amber, clear to very slightly
                                   opalescent.
Prepared Appearance:    Light to medium amber, clear to very slightly
                                   opalescent.
Reaction of 3.4%
Solution at 25°C:           pH 7.2 ± 0.2
Cultural Response
AC Broth
Prepare the medium per label directions. Inoculate and incubate at 35 ± 2°C for 18-48 hours.

Principles of the Procedure

Peptone, beef extract and malt extract provide the carbon and nitrogen sources required for good growth of a wide variety of organisms. Vitamins and cofactors required for growth as well
as additional sources of nitrogen and carbon are provided by yeast extract. Dextrose is a carbon energy source. Ascorbic acid is added to clarify the solution.

Formula

AC Broth
Approximate Formula* Per Liter
Proteose Peptone No. 3.............................................. 20.0 g
Beef Extract................................................................ 3.0 g
Yeast Extract.............................................................. 3.0 g
Malt Extract................................................................ 3.0 g
Dextrose.................................................................... 5.0 g
Ascorbic Acid............................................................... 0.2 g
*Adjusted and/or supplemented as required to meet performance criteria.

Directions for Preparation from Dehydrated Product

1. Dissolve 34 g of the powder in 1 L of purified water.
2. Autoclave at 121°C for 15 minutes.
3. Store prepared medium at 15-30°C.
4. After prolonged storage, reheat in flowing steam or a boiling water bath for a few minutes to drive off dissolved gases. Cool without agitation.
5. Test samples of the finished product for performance using stable, typical control cultures.

Procedure

See appropriate references for specific procedures.

Expected Results

Refer to appropriate references and procedures for results.

Limitation of the Procedure

When reheating prepared media to drive off dissolved gases, do not overheat because this may result in decreased growth.

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