Abstract
The aim is to elucidate if high productivity in aquatic systems leads to increased abundance of predation resistant and potentially pathogenic bacteria, such as the tularemia bacterium Francisella tularensis. Outbreaks of this bacterium, has been associated to nutrient rich stagnant waters and mosquito bites. In the proposed project we will use molecular probes for F. tularensis to study its distribution in natural waters in an emerging tularemia area, the Örebro area. The aim is to identify environmental factors, e.g. nutrient status and protozoan abundance, governing the occurrence of the bacterium. We further intend to study occurrence of general predation-resistance in bacteria in the same productivity gradient, by performing transplantation experiments. Microcosm experiments will be performed where the fate of F. tularensis is studied using natural lake water including the microbial food web and mosquito larvae as top predator. The coupling between bacterial predation-resistance and pathogenicity will be approached by comparing molecular mechanisms for predation-resistance in protozoa and human macrophages, and by studying if prolonged protozoan grazing can induce a simultaneous increased resistance to degradation by protozoa and human macrophages. If this is the case we can prove that natural aquatic systems with a high protozoan predation-pressure constitute a biological gym for the evolution of pathogenic bacteria.
Sweden