COLIKAT RAPID® is a fast test to simultaneously
detect both total coliforms and Escherichia coli in water samples providing the
test’s results within 18 hours. COLIKAT RAPID® is suited for the entire water
matrix.
Test Principle
COLIKAT RAPID® uses certain specific characteristics of both
Escherichia coli and coliform bacteria for identification of the species. The
test contains MUG and ONPG, two common nutritional indicators. Coliform
bacteria use their enzyme β-Galactosidase to metabolize ONPG turning the sample
yellow. Escherichia coli – other then most coliform bacteria – additionally has
the enzyme β-Glucuronidase that enables it to hydrolyze MUG so that the sample
additionally shows fluorescence under UV-light.
Most of non-coliform bacteria possess neither the
β-Galactosidase nor the β-Glucuronidase. Therefore, they cannot transform MUG
and ONPG and the test will not detect them. Yet, some non-coliform bacteria
contain the enzymes. COLIKAT RAPID® therefore uses selective supplements that
inhibit the growth of those bacteria. The combination of the test’s enzymes and
selective supplements prevents some common problems of conventional culture
methods such as Chromogen Coliform Agar CCA (EN ISO 9308-1):