Dextrose Tryptone Broth

Dextrose Tryptone Broth is used for cultivation of mesophilic or thermophilic spoilage microorganisms from food in a laboratory setting. Dextrose Tryptone Broth is not intended for use in the diagnosis of disease or other conditions in humans.

In the 1930's, the National Canners Association specified use of Dextrose Tryptone Agar 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 ends of the can remain flat. B. coagulans is a soil microorganism, and found in canned tomato products and dairy products. Conditions favorable for multiplication of the bacterium can result in spoilage of the food product.

Dextrose Tryptone Broth is similar to Dextrose Tryptone Agar, except the concentration of Tryptone and Dextrose has been doubled and Agar is removed. The American Public Health Association and Baumgartner and Herson recommended this formulation for the bacteriological examination of low and medium-acid canned foods (pH 4.5 and above).


Formula Liter
Enzymatic Digest of Casein 20 g
Dextrose 10 g
Bromcresol Purple 0.04 g

Final pH: 6.7 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.


  1. Dissolve 30 g of the medium in one liter of purified water.
  2. Mix thoroughly.
  3. Autoclave at 121°C for 15 minutes.

Order Details

Product # Product Description
7338A Dextrose Tryptone Broth, 500 g
7338T Dextrose Tryptone Broth, 5 kg