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Enhanced Tetrazolium Violet Reduction of Salmonella Spp. By Magnesium Addition to the Culture Media

Thomas Junillon, Lucie Morand, Jean Pierre Flandrois

Food Microbiol. 2014 Sep;42:132-5.

PMID: 24929728

Abstract:

Tetrazolium salts (TTZ), such as tetrazolium violet (TV), have been widely used for microbiological studies. The formation of the colored formazan product due to bacterial reduction of the uncolored reagent is extensively exploited to stain cells or colonies in agar or on filters. But an important toxic effect of tetrazolium salts on bacteria exists that limits their use at high concentrations, impairing the efficient staining of the colonies. This is especially the case for Salmonella spp. where we observed, using a classic photometric approach and mathematical modeling of the growth, an important impact of tetrazolium violet on the apparent growth rate below the inhibitory concentration. In this study, we demonstrate that adding magnesium to the medium in the presence of TV leads to a significant increase in the apparent growth rate. Moreover, when higher TV concentrations are used which lead to total inhibition of Salmonella strains, magnesium addition to the culture media allows growth and TV reduction. This effect of magnesium may allow the use of higher TTZ concentrations in liquid growth media and enhance bacteria detection capabilities.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP1719717 Tetrazolium Violet Tetrazolium Violet 1719-71-7 Price
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