Standard Reference Materials for Microbiological Assays

When the American Type Culture Collection (ATCC) was founded in 1925, one of its chief roles was to be a source of standards. In this context we mean standard organisms, rather than standard materials or chemicals known as Reference Materials or Certified Reference Materials and issued in the USA by the National Bureau of Standards (NBS). The National Bureau of Standards evolved into NIST and the abbreviation SRM became a trade mark of NIST. 

ATCC biological standards were known as Type Strains (TS), but as they are used in the same ways as, and fill many of the requirements for, RMs we have described them in this article as biological RMs. 

Unlike chemicals, microorganisms are living materials, so growth conditions, the physiological state of the cells, and their metabolic activities will all influence the results of tests in which they may be used. 

The reproducibility of a determination is a critical element of a standard method, so they are carefully written to ensure that they can be followed accurately by any qualified laboratory. The designated test biological RMs must not only be reproducible in their reactions to the performance tests, but they must also respond in a predicable manner. In order to guarantee that the same strain of microorganisms could always be available, many of these biological RMs have been deposited with the ATCC and other culture collections around the world. 

Around the world there are hundreds of official methods from various government and professional sources that specify ATCC microorganisms as biological RMs. The following six examples serve as examples of many organizations arotmd the world that specify ATCC microbial cultures as biological RMs  

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