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TRYPTONE SOYA AGAR (Casein soya bean digest agar) EP/USP/JP/BP

Code: CM0131

a general purpose medium for the growth of a wide variety of organisms



Pancreatic digest of casein


Enzymatic* digest of soya bean


Sodium chloride




pH 7.3 ± 0.2 @ 25°C


*Contains papain

Add 40g to 1 litre of distilled water (purified as required). Bring to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes.

A general purpose agar medium, containing two peptones, which will support the growth of a wide variety of organisms. It is suitable for the cultivation both of aerobes and anaerobes, the latter being grown either in deep cultures or by incubation under anaerobic conditions. The medium may also be used as a blood agar base - for this purpose 7% of sterile blood should be added to the sterile molten medium which has been cooled to approximately 45°C. Tryptone Soya Agar can also be used for the preparation of `chocolate’ agar.

Since Tryptone Soya Agar contains no added carbohydrate it may be used, with added blood, in the determination of haemolysis. Horse blood agar plates prepared with Tryptone Soya Agar are used for the colicine typing of Shigella sonnei 1,2,3,4.

The Oxoid medium has also been used as a replacement for yeastrel-milk agar plates in the Lisboa test 5 and for bacterial counts on eviscerated poultry6.

When supplemented with 0.7g lecithin and 5g Polysorbate (Tween 80) per litre of Tryptone Soya Agar, the medium can be used as Microbial Content Test Agar for testing quaternary ammonium compounds7.

Tryptone Soya Agar is recommended as a reference medium when testing selective media, to measure the degree of inhibition8.

A medium for isolation of Bacteroides gracilis is prepared from Tryptone Soya Agar by adding formate, fumarate and nitrate. The medium is made selective using nalidixic acid and teicoplanin9.

Enhanced haemolysis agar (EHA) used to improve detection of Listeria monocytogenes when present amongst other listeriae has been modified to optimise its performance by substituting Tryptone Soya Agar for Columbia Agar in the original formulation10. Tryptone Soya Agar conforms to formulations detailed in various international pharmacopoeia11,12,13,14.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared plates of medium at 2-8°C.

Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Light straw to straw coloured gel

Quality control  - non-pharmaceutical testing

Positive controls:

Expected results

Staphylococcus aureus ATCC® 25923 *

Good growth; straw coloured colonies

Streptococcus pyogenes ATCC® 19615 *

Good growth; pale straw coloured colonies

Negative control:


Uninoculated medium

No change

* This organism is available as a Culti-Loop™

Quality control - pharmaceutical testing

Micro-organismPreparation of StrainGrowth promotion and suitability of the counting method in presence of product

Staphylococcus aureus ATCC® 6538*

TSA (casein soya bean digest agar) at 30-35°C for 18-24 hours<100 CFU in TSA (casein soya bean digest agar) at 30-35°C for ≤3 days
Pseudomonas aeruginosa ATCC® 9027*
Bacillus subtilis ATCC® 6633*
Candida albicans ATCC® 10231*

Sabouraud Dextrose Agar (R454462) or Sabouraud
Dextrose Liquid Medium (CM0147) at 20-25°C for 2-3 days

<100 CFU in TSA (casein soya bean digest agar) at 30-35°C for ≤5 days
Aspergillus brasiliensis ATCC® 16404*Sabouraud Dextrose Agar (R454462) or Potato Dextrose Agar(CM0139) at 20-25°C for 5-7 days, or until good sporulation is achieved
*     This organism is available in Quanti-Cult™ format

It should be noted that haemolytic reactions of streptococci on Tryptone Soya Agar can vary according to the origin of the blood e.g. horse or sheep. Tryptone Soya Agar designed for sheep blood show significant differences when used with horse blood and vice versa.

1. Abbott J. D. and Graham J. M. (1961) Mon. Bull. Min. Hlth Pub. Hlth Lab. Serv. 20. 51-58.
2. Barrow G. I. and Ellis C. (1962) Mon. Bull. Min. Hlth Pub. Hlth Lab. Serv. 21. 141-147.
3. Cooke G. T. and Daines C. F. (1964) Mon. Bull. Min. Hlth Publ. Hlth Lab. Serv. 23. 81-85.
4. Gillies R. R. (1964) J. Hyg. Camb. 62. 1-9.
5. Mitchell T. G. (1964) J. Appl. Bact. 27. 45-52.
6. Barnes Ella M. and Shrimpton D. H. (1958) J. Appl. Bact. 2. 313-329.
7. American Public Health Association (1978) Standard Methods for the Examination of Dairy Products. 14th Edn. APHA Inc. Washington DC.
8. Anon. (1987) J. Food Microbiol. 5. 291-296.
9. Lee K., Baron E.J., Summanen P. and Finegold S. (1990) J. Clin. Microbiol. 28. 1747-1750.
10. Beumer R.R., te Giffel M.C. and Cox L.J. (1997) Lett. Appl. Microbiol. 24. 421-425.
11. British Pharmacopoeia Volume II (2000)
12. US Pharmacopoeia XXX, (2008)
13. European Pharmacopoeia. 6.1 Edition (2008)
14. Japanese Pharmacopoeia. 15th Edition. (2006)

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