CRITERION™ DEXTROSE TRYPTONE AGAR
|Cat. no. C5620||CRITERION™ Dextrose Tryptone Agar||60gm|
|Cat. no. C5621||CRITERION™ Dextrose Tryptone Agar||500gm|
|Cat. no. C5622||CRITERION™ Dextrose Tryptone Agar||2kg|
|Cat. no. C5623||CRITERION™ Dextrose Tryptone Agar||10kg|
|Cat. no. C5624||CRITERION™ Dextrose Tryptone Agar||50kg|
Hardy Diagnostics CRITERION™ Dextrose Tryptone Agar is used for cultivating thermophilic "flat-sour" microorganisms associated with food spoilage.
This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.
Dextrose Tryptone Agar is used for isolating "flat-sour" organisms from food products. "Flat-sour" spoilage of canned foods is caused by Bacillus coagulans ( Bacillus thermoacidurans). Bacterial growth results in a 0.3-0.5 drop in pH, while the ends of the can remain flat.
B. coagulans is a soil microorganism that can be found in canned tomato products and dairy products. Conditions favorable for multiplication of the bacterium can result in spoilage of the food product.(2)
Dextrose Tryptone Agar can also be used to isolate other food spoilage bacteria: mesophilic aerobic spore-formers in the genera Bacillus and Sporolactobacillus and thermophilic "flat-sour" spore-formers such as B. stearothermophilus.(2)
|Gram weight per liter:||30.0gm/L|
Final pH 6.7 +/- 0.2 at 25ºC.
* Adjusted and/or supplemented as required to meet performance criteria.
STORAGE AND SHELF LIFE
Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original light greenish-beige.
Store the prepared media at 2-8ºC.
METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA
1. Suspend 30.0gm of the dehydrated culture media in 1 liter of distilled or deionized water.
2. Heat to boiling and mix to dissolve completely.
3. Sterilize in the autoclave at 121ºC. for 15 minutes.
4. Cool to 45-50ºC. Aseptically dispense into sterile petri dishes.
PROCEDURE AND INTERPRETATION OF RESULTS
For information on procedures and interpretation of results, consult listed references.
MATERIALS REQUIRED BUT NOT PROVIDED
Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.
|Test Organisms||Inoculation Method*||Incubation||Results|
ATCC ® 12980
|A||36-48hr||55°C||Aerobic||Growth; color change from purple to yellow|
User Quality Control
CRITERION™ Dextrose Tryptone Agar powder should appear homogeneous, free-flowing and light greenish-beige in color. The prepared media should appear slightly opalescent, without significant precipitate, and purple in color.
1. National Canners Association. Bacterial standards for sugar. 1933.
2. Vanderzant, C. and D.F. Splittstoesser, (ed.). 1992. Compendium of Methods for the Microbiological Examination of Foods, 3rd ed. American Public Health Association, Washington, D.C.
ATCC is a registered trademark of the American Type Culture Collection.