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Comparison of the fluorescent redox dye 5‐cyano‐2,3‐ditolyltetrazolium chloride with p‐iodonitrotetrazolium violet to detect metabolic activity in heat‐stressed Listeria monocytogenes cells
Author(s) -
Bovill R.A.,
Shallcross J.A.,
Mackey B.M.
Publication year - 1994
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1994.tb03434.x
Subject(s) - listeria monocytogenes , formazan , chromogenic , fluorescence , alizarin red , redox , tetrazolium chloride , viability assay , chemistry , population , microbiology and biotechnology , cell , nuclear chemistry , biochemistry , chromatography , biology , staining , bacteria , pathology , medicine , inorganic chemistry , genetics , physics , environmental health , ischemia , quantum mechanics , cardiology
The fluorogenic redox indicator 5‐cyano‐2,3‐ditolyltetrazolium chloride (CTC) was compared with the chromogenic p ‐iodonitrotetrazolium violet (INT) and conventional methods to assess cellular viability. Mild heat treatment was used as a well‐controlled method for producing non‐viable and sub‐lethally injured cells. CTC gave an underestimation of the viability of Listeria monocytogenes cells when compared with classical plating methods whereas INT gave an overestimation. However, CTC proved to be a sensitive indicator of uninjured cells. The difference between the total count and the CTC count was equivalent to the injured cell population. The fluorescent formazan formed on reduction ofCTC was readily detected with a charge coupled device and cells enumerated automatically using image analysis.