Methods for detection and quantification of polyphosphate and polyphosphate accumulating microorganisms in aquatic sediments

It has been speculated that the microbial P pool is highly variable in the uppermost layer of various aquatic sediments, especially when an excessive P accumulation in form of polyphosphate (Poly-P) occurs. Poly-P storage is a universal feature of many different organisms and has been technically optimised in wastewater treatment plants (WWTP) with enhanced biological phosphorus removal (EBPR). In the recent past, new insights into mechanisms of P elimination in WWTP almost exclusively depended on the development and application of novel methods like P-31-NMR spectroscopy and molecular methods for identifying Poly-P accumulating microorganisms (PAO). The aim of the present review is to compile current methods potentially available for detection and quantification of Poly-P in sediments and to complement it with yet unpublished results to validate their application in natural sediments. The most powerful tool for reliable Poly-P quantification in sediments is the liquid P-31-NMR technique which has been successfully used for Poly-P measurements in a variety of aquatic sediments. But the microorganisms as well as mechanisms involved in Poly-P storage and cycling are largely unknown. Therefore, we also intend to stimulate future studies focusing on these encouraging topics in sediment research via the implementation of novel methods.