Generalized indicator plate for genetic, metabolic, and taxonomic studies with microorganisms

B. R. Bochner, M. A. Savageau

Research output: Contribution to journalArticlepeer-review

159 Scopus citations


We have developed an indicator plate that works well for diverse types of substrates and microorganisms. The plates are inexpensive and easy to prepare. The essential components are agar, buffer, growth-supporting nutrients, a test substrate, and 2,3,5-triphenyl tetrazolium chloride (TTC). Using various strains of Salmonella typhimurium and Escherichia coli, we have studied and defined the contribution of each component to the satisfactory function of the plate. Colonies capable of catabolizing the test substrate reduce TTC and produce a deep red formazan, whereas colonies failing to catabolize the substrate remain uncolored. Those with intermediate rates of catabolism differ in rate and/or extent of color formation. In all cases the color is stable because TTC reduction is essentially irreversible. Since the mode of action of these plates is fairly well understood, alternative formulations can be devised to meet specific needs. The general applicability of this TTC indicator system makes it an extremely useful tool in microbial genetics, metabolism, and taxonomy.

Original languageEnglish (US)
Pages (from-to)434-444
Number of pages11
JournalApplied and Environmental Microbiology
Issue number2
StatePublished - 1977
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Science(all)
  • Microbiology


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