Bacterial Tester Strains

Bottles with STDiscs and ECDiscs

For microbial genotoxicity assays utilized as culture inoculum

The Ames test1 originally utilized strains of the bacteria Salmonella typhimurium that carry mutations in genes involved in histidine synthesis. These strains are auxotrophic mutants, i.e. they require histidine for growth, but cannot produce it. The method tests the capability of the tested substance in creating mutations that result in a return to a "prototrophic" state, so that the cells can grow on a histidine-free medium.
A few years later, Green and Muriel2 established an analog test system for E. coli strains.

  • All bacterial discs in the catalog were prepared from master cultures obtained from Dr. Bruce Ames1 and the NCIMB - National Collections of Industrial, Food and Marine Bacteria Limited, Aberdeen; Scotland, UK
  • The S. typhimurium and E. coli strains are lyophilized and stabilized according to ATCC and OPS Diagnostics
  • The strains are fully characterized for phenotypic characteristics and respond to diagnostic mutagens as required by OECD guideline 4714. The average CFU (colony forming unit) per disc is included in the QC documents


Salmonella typhimurium strains for use in the bacterial mutagenesis assay described by Maron and Ames1

Catalog no. Description Storage Size
71-097L STDisc TA97a, lyoph. 4°C 10 discs/vial
71-098L STDisc TA98, lyoph. 4°C 10 discs/vial
71-100L STDisc TA100, lyoph. 4°C 10 discs/vial
71-102L STDisc TA102, lyoph. 4°C 10 discs/vial
71-1535L STDisc TA1535, lyoph. 4°C 10 discs/vial
71-1537L STDisc TA1537, lyoph. 4°C 10 discs/vial
71-1538L STDisc TA1538, lyoph. 4°C 10 discs/vial


Escherichia coli strains (WP2 derivatives) for use in the bacterial mutagenesis assay described by Green et al.2

Catalog no. Description Storage Size
72-002L ECDisc WP2 trp, pKM101, lyoph. 4°C 10 discs/vial
72-003L ECDisc WP2 trp, uvrA, pKM101, lyoph. 4°C 10 discs/vial
72-187L ECDisc WP2 trp, lyoph. 4°C 10 discs/vial
72-188L ECDisc WP2 trp, uvrA, lyoph. 4°C 10 discs/vial


Salmonella strain for use in the SOS/UMU test as described by Oda et al.3

Catalog no. Description Storage Size
73-1535psK PTM Salmonella typhimurium TA1535/pSK1002 -80°C 1 ml/vial

Salmonella typhimurium strain TA1535/pSK1002 is offered in proprietary transport medium (PTM).

STDiscs/ECDiscs- Product Information (PDF, 453 KB)

For phenotype confirmation use kit #31-600

Please note:
In Germany S. typhymurium and E. coli bacterial strains are classified as animal disease pathogens (epizootic pathogens) of risk group 1. Please check for appropriate regulations in your country!
The bacterial strains contained in STDiscs and ECDiscs are potential etiologic agents and are intended for use only by those skilled in the safe handling of potentially infectious agents.

according to the German “Gentechnikgesetz” TA102 and TA1535/pSK1002 have been classified as “genetically modified organism” (GVO/GMO) of risk group 1/BSL1.

1 Maron D., Ames B. Revised methods for the Salmonella mutagenicity test. Mutation Research 113(3-4):173-215, 1983.
2 Green M.H., Muriel W.J. Mutagen testing using TRP+ reversion in Escherichia coli. Mutation Research 38(1):3-32, 1976.
3 Oda Y., Nakamura S., Oki I., Kato T., Shinagawa H. Evaluation of the new system (umu-test) for the detection of environmental mutagens and carcinogens. Mutation Research 147(5):219-29, 1985.
4 OECD Guideline 471 for the Testing of Chemicals, Section 4. Test No. 471: Bacterial Reverse Mutation Test.