[Effect of the isolation medium and isolation conditions on the isolation of the bacterial species spectrum in drinking water].

With the method of colony-count estimation according to German standards (Trinkwasserverordnung, TVO), bacteria of the genera Aeromonas, Shewanella, Pseudomonas etc. and (if present) representatives of the family Enterobacteriaceae can be detected. Longer incubation and application of low nutrient media enhance the colony counts up to 100-fold, and other bacteria can be isolated, in most cases belonging to the genera Pseudomonas, Alcaligenes, Acinetobacter, Flavobacterium etc.. For the detection of hygienically relevant bacteria (e.g. indicator bacteria) the methods of TVO are sufficient and their routine use is recommended. For further microbiological-ecological studies on the habitat drinking water, the nutrient poor biotope has to be considered and the applied media and methods should be adapted to these requirements.