Der GMOfinder - DLR Online: Deutsche Lebensmittel Rundschau
Der GMOfinder - DLR Online: Deutsche Lebensmittel Rundschau
Der GMOfinder - DLR Online: Deutsche Lebensmittel Rundschau
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652 Sonderthema: Mikrobiologische Methoden in der <strong>Lebensmittel</strong>analytik «<br />
Microorganisms in liquid samples<br />
Simple testing options exist to detect or<br />
enumerate microorganisms<br />
Rolf Steinmüller<br />
Testing liquid samples, including water, for microorganisms presents challenges not<br />
seen in testing other sample types. Water samples often contain viable microorganisms<br />
injured by chlorine treatment, and liquid samples in general present a challenge to collect<br />
representative test samples. We offer a choice of test systems to detect, or enumerate,<br />
microorganisms in challenging liquid samples.<br />
Dr. Rolf Steinmüller<br />
» Contact<br />
Dipl.-Biologe, Division<br />
Manager Germany,<br />
Neogen Europe Ltd.<br />
«<br />
The Colitag (Presence/Absence) Water<br />
Test Kit uses an U.S. Environmental Protection<br />
Agency (EPA)-approved selective<br />
and differential medium to detect total<br />
coliforms and E. coli in water and liquid<br />
samples in as little as 16 hours.<br />
The Filter is a disposable membrane<br />
filtration system that uses ampouled media<br />
to detect and provide quantitative<br />
results for a wide variety of microorganisms<br />
in liquid samples. The new disposable<br />
system utilizes cellulose membrane<br />
filter technology, and ampouled liquid<br />
media, to detect and quantify target organisms.<br />
The system is available with either<br />
white or black filters, and each lid has<br />
a magnifying circle to make the small colonies<br />
easier to identify. Various 2 mL media<br />
ampoules are available for use with<br />
the system to detect a variety of microorganisms<br />
in a variety of liquid sample types.<br />
A testing method to detect<br />
coliforms and E. coli in water<br />
Colitag represents the next generation of<br />
tests to detect potentially dangerous coliforms.<br />
Unlike other tests, Colitag’s patented<br />
system resuscitates and detects chlorine-injured<br />
coliforms, including E. coli.<br />
Other tests can miss these weakened coliforms,<br />
which may include bacteria capable<br />
of causing human illness.<br />
The system allows users to easily go beyond<br />
simple coliform detection at the level<br />
of 1 colony forming unit (CFU) per 100 mL.<br />
It also allows the simultaneous identification<br />
of the coliform of utmost concern,<br />
E. coli. Simply detecting coliforms provides<br />
a good indication of the overall sanitation<br />
level of a facility. But, solely detecting<br />
coliforms does not indicate whether<br />
the coliforms that were found are innocuously<br />
environmental, or the more potentially<br />
dangerous E. coli.<br />
Fecal coliforms and E. coli can be detected<br />
using the Colitag system, if<br />
4-methylumbelliferyl-β-D-glucuronide<br />
(MUG) positive E. coli are present in the<br />
sample, a bright blue fluorescence will be<br />
seen when subjected to ultraviolet light.<br />
The sample may also be checked for indole<br />
positive E. coli, by adding Kovac’s reagent.<br />
A reddish-purple colour will form on the<br />
surface of the solution with the presence<br />
of indole positive E. coli.<br />
After a single 24-hour incubation, and<br />
with very little extra effort, the assay<br />
allows users to go beyond coliform de-<br />
» Dezember 2012 | <strong>DLR</strong>