Occurrence of Legionella pneumophila and Hartmannella vermiformis in fresh water environments and their interactions in biofilms

Legionella pneumophila, the causative agent of Legionnaires’ disease, is widespread in natural fresh water environments and is also frequently found in man-made water systems. Microbial biofilms and protozoa are known to play a major role in the proliferation of L. pneumophila. Biofilms provide shelter and a gradient of nutrients, and protozoa may act as host for L. pneumophila, since intracellular multiplication of L. pneumophila was shown in a variety of protozoan species. The need for protozoa for the proliferation of L. pneumophila in aquatic habitats is still not fully understood and is even questioned by some investigators. This thesis shows the in vivo growth of L. pneumophila in protozoa in aquatic biofilms developing at high population densities on plasticized polyvinylchloride in a biofilm-batch model system with autoclaved tap wate