This application note provides information on specific application methods and the use of Hettich products. (more…) read more...
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Drinking water has to satisfy strict requirements in terms of the micro-organisms it can contain. The total number of culturable micro-organisms is one parameter that has to be determined. The colonies that are to be counted include those isolated from humans and animals as well as those found in the soil or water. The results of such colony counts allow inferences to be drawn on the nature and origin of the colonies. 1ml water must not contain more than 100 colonies.
METHOD OF CULTURE
The micro-organisms are cultured as given in ISO 6222: 1999 through inoculation into nutrient agar medium and incubation at 22 °C for soil organisms and at 36 °C for organisms isolated from humans or animals. The colonies are then counted with the naked eye. The German Drinking Water Act also permits a different plating method in which the colonies are counted under magnification of 6x to 8x, and the duration of incubation at 22 °C is 44 ± 4h.
IMPORTANCE OF COLONY COUNTS IN PRACTICE
Drinking water is tested at regular intervals to protect consumers, and the testing includes colony counts. The nature and type of testing is specified in national regulations such as the “Trinkwasserverordnung” in Germany and the Safe Drinking Water Act in the USA.
Incubation conditions are given in ISO 6222:1999
ADVANTAGES OF HETTCUBE INCUBATORS
Hettich products are designed to help you achieve optimal results for your application and are built to perform to the specifications outlined in the operators manual. For application-specific information and settings, please refer to your organization’s standard operating procedure. As always, our Hettich representatives are here to help determine which Hettich products and accessories best fit your laboratory requirements.
Hettich Hettcube incubators and cooled incubators are built to maximize their compact footprint with efficient design features that improve temperature uniformity, operational performance, and user interaction.
Hettich HettCube incubators offer many advantages for an efficient workflow.