Treatment of water for aquatic bacterial growth studies.

The composition of a water is inextricably linked to its nutrient status and hence influences the behaviour of bacteria in artificial water systems. It has not yet been possible to devise a defined liquid medium representative of the complex composition of a treated water. Instead sterilized natural or distilled waters are used to study the growth or survival of aquatic bacteria in the laboratory. This has led to conflicting data and opposing opinions when the same water has proved toxic in some laboratory studies and growth-supporting in others. These differences may be explained by the variations in chemical compositions which occur when water is collected, transported and treated or stored in the laboratory. This study describes a simple, membrane filtration method of preparing a fresh sample of water collected from the environment or a building water system such that it is both sterile and chemically unaltered. The availability of such water may enhance understanding of the behaviour of bacteria in the aquatic environment.