Molecular analyses of bacterial communities in drinking water and biofilms - seasonal dynamics, viability and community composition of cold and hot water

Although water treatment and disinfection measures aim at eliminating all harmful mircroorganisms, the water quality at the customer tap does not necessarily provide the same quality as the water leaving the waterworks facility. It still provides an environment for a regrowing microflora. The objective of the present thesis was to get insights into the bacterial drinking water communities and their associated habitats (e.g biofilms and hot water). Therefore, it is of relevance, which environmental factors are influencing the presence and activity of the members of these communities and what interactions exist between these communities. In the first two parts of the thesis we investigated the bacterial dynamics in the drinking water of Braunschweig, Germany, over the timeframe of 18 month. Using SSCP-fingerprints and sequencing major bands we analysed the seasonal dynamics of the community composition and its activity of cold and hot drinking water ot the the campus of the Helmholtz Centre for Infection Research (HZI) in relation to meteorological data of the catchment area. For cold drinking water it was demonstrated that the precipitation was the major impact influencing the amount and activity of bacteria. The hot drinking was mainly composed of thermophilic and thermotolerant bacteria. In the third part a detailed analysis of the bacterial community in biofilms and corresponding bulk water was done. The bacteria in all biofilm samples showed a highly different structure with no overlap to the phylotypes observed in bulk water. Biofilms sampled on nearby sampling points showed similar communities in spite of different support materials. In the fourth part we investigated which bacterial species are present in drinking water. Therefore a combination of Live/Dead-staining, FACS and community fingerprinting was used for the analysis of drinking water samples. The developed approach enabled the assessment of the physiological state of taxonomic groups of interest.