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Colitag™ 16-48 Hour P/A Test for Total
Coliforms and E. coli in Drinking Water
Product Overview
Colitag™ is a selective and differential medium
for the determination of the presence or absence of total coliforms
and E. coli in drinking water. It is a one-step, ready to
use medium, to be combined with a water sample. This product is
designed to test water samples for total coliform and/or E. coli
bacteria within a 16 to 48 hour window and does not require further
confirmation or verification steps. Colitag™ detects 1
colony-forming unit (CFU) of E. coli and other total coliform
bacteria in 100mL of water.
Method Summary:
For sample reading between 16 to 22 hours:
1. Aseptically add the Colitag™ to a 100-mLtest water sample in a
sterile vessel.
2. Secure vessel top and agitate to begin dissolution.
3. Incubate the sample at 35 °C ± 0.5 °C for 22 to 48 hours.
4. Read results according to the sample interpretation method listed
below.
1. Aseptically add the Colitag™ to a 100-mLtest water sample in a
sterile vessel.
2. Secure vessel top and agitate to begin dissolution.
3. If sample is not already at 33-38°C, then place vessel in a
44.5°C water bath for 7 to 10
minutes.
4. Incubate sample at 35 °C ± 0.5 °C for the remainder of the
desired incubation time, 16 to 22
hours.
5. Read results according to the sample interpretation method listed
below.
For sample reading between 22 to 48 hours:
1. Aseptically add the Colitag™ to a 100-mL test water sample in a
sterile vessel.
2. Secure vessel top and agitate to begin dissolution.
3. Incubate the sample at 35 °C ± 0.5 °C for 22 to 48 hours.
4. Read results according to the sample interpretation method listed
below.
The Colitag™ method is based on the detection of
two enzymes, ß-glucuronidase and ß-galactosidase, which are
characteristic of E. coli and the coliform groups, respectively.
Colitag™ detects total coliforms using the chromogenic substrate
ortho-nitrophenyl-ß-D-galactopyranoside (ONPG). Upon hydrolysis by
ß-galactosidase, ONPG produces a distinct yellow color, confirming
the presence of coliforms in the sample.
For detection of E. coli, Colitag™
utilizes the fluorogenic enzyme substrate
4-methylumbelliferyl-ß-D-glucuronide (MUG). Upon hydrolysis by ß-glucuronidase,
MUG releases 4methylumbelliferone. This reaction by-product
fluoresces when exposed to UV light. The ß-glucuronidase enzyme is
specific to E. coli and observation of fluorescence
differentiates this organism from other members of the coliform
group.
Only the Colitag method offers a patented
technology called “acid resuscitation” for increased test
sensitivity. In this cutting edge technology, a small amount of acid
works together with specialized nutrients to resuscitate weak and
injured E. coli and other total coliform cells.
Only Colitag offers the longest testing window of
16 to 48 hours and the most versatile total coliform and E. coli
test in the world.
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