DEVELOPMENT OF A RAPID METHOD FOR THE ENUMERATION OF BACTERIA IN POTABLE WATER

Two viability substrates, ChemChrome B and 5-cyano-2,3,4-tolyl-tetrazo lium chloride (CTC) were compared with the traditional pour plate meth od for the enumeration of bacteria in potable water samples. ChemChrom e B stained cells were counted, on a membrane, using a novel laser sca nning device whereas CTC stained cells were counted using epifluoresce nce microscopy. A significantly higher number of bacteria were detecte d using the viability assays than by culture, which highlights the ine fficiency of current culture techniques. Results with ChemChrome B ill ustrate that the use of a laser scanning device provides an efficient method for the enumeration of fluorescently labelled microorganisms. ( C) 1997 IAWQ. Published by Elsevier Science Ltd.