Polyphosphate in marine environments and Beggiatoa sp. : quantification and visualization Polyphosphate has been increasingly recognized in recent years as an important component of the microbial phosphorus cycle. Quantification of polyP in coastal waters showed a permanent presence of polyP. In addition polyP stored by bacteria of the genus Beggiatoa in sediments off Peru has the potential to contribute to sedimentary phosphate fluxes. It was possible to demonstrate the activity of the intracellular phosphorus pool with a new method established in laboratory studies with the model organisms Beggiatoa sp. 35Flor. This revealed a permanent active cellular recycling of polyP.<eng>