Locomotion of a bacterium with a polar bundle of flagella : insights into movement and navigation by fluorescence high speed microscopy Movement and navigation are essential for many organisms during some parts of their lives. This is also true for bacteria which can move along surfaces and swim though liquid environments. They are able to sense their environment and move towards environmental cues in a directed fashion. These abilities enable microbial lifecyles in biofilms improved food uptake host infection and many more. In this thesis we study aspects of the swimming movement or motility of the soil bacterium (P. putida). Like most bacteria P. putida swims by rotating its helical flagella but their arrangement differs from the main model organism in bacterial motility research: (E. coli). P. putida is known for its intriguing motility strategy where fast and slow episodes can occur after each other. Up until now it was not known how these two speeds can be produced and what advantages they might confer to this bacterium. Normally the flagella the main component of thrust generation in bacteria are not observable by ordinary light microscopy. ...