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An in situ method for determining bacterial survival on food preparation surfaces using a redox dye
Author(s) -
Barnes B.I.,
Cassar C.A.,
Halablab M.A.,
Parkinson N.H.,
Miles R.J.
Publication year - 1996
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.1996.tb00200.x
Subject(s) - redox , in situ , chemistry , bacteria , microbiology and biotechnology , biophysics , environmental chemistry , biology , inorganic chemistry , organic chemistry , genetics
A simple method is described for the direct enumeration of viable bacteria dried on test surfaces. Inoculated surfaces were overlayed with agar and after incubation nitroblue tetrazolium solution (pale yellow) was used to stain colonies (purple) at the agar‐test surface interface. Stained colonies could be readily detected and counted even against the opaque background of ceramic tile or stainless steel or when present within opaque films of milk or serum. Recovery of bacteria by this method was approximately fivefold greater than using a conventional swabbing procedure. The method was used to demonstrate the marked effect of the composition of the suspension fluid, in which bacteria were dried, and the length of surface exposure upon bacterial survival.