Cat. no. C7500 CRITERION™ Fluid Thioglycollate Media 59.6gm
Cat. no. C7501 CRITERION™ Fluid Thioglycollate Media 500gm
Cat. no. C7502 CRITERION™ Fluid Thioglycollate Media 2kg
Cat. no. C7503 CRITERION™ Fluid Thioglycollate Media 10kg
Cat. no. C7504 CRITERION™ Fluid Thioglycollate Media 50kg


Hardy Diagnostics CRITERION™ Thioglycollate medium are recommended for the cultivation of aerobic, microaerophilic, and anaerobic microorganisms.

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.


The Fluid Thioglycollate Medium formulation was first described in 1940 by Brewer.(1) This medium demonstrated that combining a small amount of agar and a reducing substance initiated the growth of anaerobic bacteria. The Fluid Thioglycollate Medium formulation is the standard medium recommended by the Food and Drug Administration, National Institute of Health, the National Formulary, and the U.S. Pharmacopeia for sterility testing of clear fluid biologics and other sterile products.(2,4,5,7) Alternatively, Fluid Thioglycollate Medium is used for sterility testing of turbid biological specimens.

The addition of a small amount of agar in Thioglycollate Medium aids in the initiation and growth of small inocula and anaerobes by impeding the diffusion of oxygen into the medium. It also retards the dispersion of CO2 and the reducing substance from the microenvironment surrounding the inoculum. Sodium thioglycollate is a reducing agent which maintains a low oxygen tension by removing molecular oxygen from the environment. Peroxides, which may be lethal to many anaerobic organisms, are not formed under this condition. Cystine and casein supply carbon and nitrogenous compounds, dextrose is added as another energy source, and sodium chloride maintains osmotic equilibrium.

Certain additives can be incorporated into the Thioglycollate Medium as desired. Yeast extract or papaic digest of soybean meal can be added as growth enhancers.


Gram weight per liter: 29.8gm/L
Agar 0.75gm
Pancreatic Digest of Casein 15.0gm
Yeast Extract 5.0gm
Dextrose 5.5gm
Sodium Chloride 2.5gm
Sodium Thioglycollate 0.5gm
L-Cystine 0.5gm
Resazurin 1.0mg

Final pH 7.1 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


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 beige.

Store the prepared culture media at 2-30ºC.



1. Suspend 29.8gm 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.


For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. K84.


In test samples, the proper surface to volume ratio of the Thioglycollate Medium must be maintained to avoid oxidation of the medium, making it unsuitable for microaerophilic and anaerobic growth.

A slight turbidity or haziness may be present due to the small amount of agar in the medium. When the media has been boiled it appears clear.

Do not boil media more than once, as frequent boiling may lead to toxic products forming in the medium.(3) If it is suspected that the medium has more than 30% oxidation after boiling, it should be discarded.


Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Staphylococcus aureus
ATCC ® 6538
J 1-3 days 35°C Aerobic Growth
Pseudomonas aeruginosa
ATCC ® 9027
J 1-3 days 35°C Aerobic Growth
Clostridium sporogenes
ATCC ® 19404
J 1-3 days 35°C Aerobic** Growth

** Tubes are incubated in an aerobic incubator with the caps screwed down tightly to create an atmosphere of low oxygen tension within the tube.

User Quality Control

Note: Thioglycollate with Indicator Media contains a resazurin indicator which will cause the upper layer of this broth to be pink, due to the exposure to oxygen. Containers that have been agitated recently will turn pink throughout. This can be reversed by allowing the container to stand still for a few hours or by putting the containers in a boiling waterbath for 10 minutes with loosened caps. The caps are then tightened firmly before the media cools. Also note that it is common for a whitish precipitate to form in this medium due to the agar content. This does not effect the performance of this medium.


CRITERION™ Fluid Thioglycollate Media, USP powder should appear homogeneous, free-flowing, and light beige in color. The prepared media should appear translucent, and amber in color. Those formulations with an indicator added will have a pink layer at the medium-air interface. If the media appears pink in color, follow the instructions given above to restore and reduce the media.


1. Brewer, J.H. 1940. J. Amer. Med. Assoc.; 115:598.

2. Federal Security Agency, Food and Drug Administration, Compilation of Regulations for Test and Methods of Assay and Certification of Antibiotic Drugs.

3. MacFaddin, J.F. 1985. Media for Isolation, Cultivation, Identification, Maintenance of Bacteria, Vol. I. Williams & Wilkins, Baltimore, MD.

4. American Public Health Association. Standard Methods for the Examination of Dairy Products, APHA, Washington, D.C.

5. National Institutes of Health Circular: Culture Media for the Sterility Test, 2nd rev. Feb. 5, 1946.

6. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.

7. U.S. Pharmacopeia, 23rd rev. 1995. U.S. Pharmacopeial Convention, Rockville, MD.

8. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

ATCC is a registered trademark of the American Type Culture Collection.