Microbial growth potential in alpine karst-groundwater

About 25% of the global community is depending on drinking water from karstic groundwater resources. As a prominent example, Vienna, the capital of Austria (about 1.6 million inhabitants), is almost exclusively supplied (>95%) by water from alpine karst aquifers. Consequently, alpine karst research has to provide the basic scientific understanding which enables to take all necessary steps for long term maintaining of the ecological integrity of the respective alpine catchment areas. In contrast to its importance only little knowledge on the ecosystem in karstic groundwater is currently available. Two years ago our group gave first evidence for the existence of an autochthonous microbial endokarst community (AMEC). Planktonic microorganisms showed very high variations in bacterial production depending on the respective hydrological situation in the system. During this project new developments in flow-cytometry achieved at the EAWAG (Swiss federal institute of water science and technology, belonging to the ETH (Eidgenössische Technische Hochschule) Zürich) will be adapted to alpine karst aquifers and established in Austria. These methods allow for the first time, for an accurate and fast determination of AOC-(assimilable organic carbon) concentration and with that for a good estimation of the biostability of the respective groundwater. This information is especially important in respect of transport and storage of the water by drinking water authorities. AOC-measurement has not been applied as a quality parameter so far, because traditional methods did not suite the purpose of a routine application. Furthermore different fluorescent dyes can be used to flow-cytometrically analyse the physiological state of the microorganisms in the water. Until now it is not clear if the microbial community in the water column of groundwater habitats is self-contained or only comprises cells that were detached or actively released from the biofilm. The roll of biofilm in groundwater systems is particularly interesting in terms of self-purification processes and biogeochemical processes taking place in the aquifer. Supplemental to the flow-cytometric investigations, PCR-DGGE (polymerase chain reaction - denaturing-gradient-gel-electrophoresis) and phylogenetic population analysis via 16S-rDNA will be used to analyse possible differences between the planktonic and the attached AMEC. These results could further help to explain the origin of cells in the water column. Hence this project would support the transfer of novel promising methods to Austria and is relevant in two aspects. On the one hand in the applied field, as the establishment of this method could help to use AOC-measurement as a routine quality parameter for drinking water. On the other hand in basic research, where it could advance the understanding of alpine karstic groundwater ecosystems and their microbial inhabitants and, at least partly, answer the question if microbial growth of planktonic AMEC is exclusively biofilm induced.