Characterisation of Phosphate Accumulating Organisms and Techniques for Polyphosphate Detection: A Review.

Cédric Tarayre,Anissa Delepierre,Huu-Thanh Nguyen,Frank Delvigne,Erik Meers,Evi Michels,Raphaëlle Charlier,Alison Brognaux,Lies De Clercq

doi:10.3390/s16060797

Abstract

Phosphate minerals have long been used for the production of phosphorus-based chemicals used in many economic sectors. However, these resources are not renewable and the natural phosphate stocks are decreasing. In this context, the research of new phosphate sources has become necessary. Many types of wastes contain non-negligible phosphate concentrations, such as wastewater. In wastewater treatment plants, phosphorus is eliminated by physicochemical and/or biological techniques. In this latter case, a specific microbiota, phosphate accumulating organisms (PAOs), accumulates phosphate as polyphosphate. This molecule can be considered as an alternative phosphate source, and is directly extracted from wastewater generated by human activities. This review focuses on the techniques which can be applied to enrich and try to isolate these PAOs, and to detect the presence of polyphosphate in microbial cells.

Highlights

Phosphorus is an essential element required for food production
Molecular techniques allowed to identify Candidatus Accumulibacter phosphatis (Rhodocyclus-related bacteria) as an important subclass involved in P removal at the lab scale, but it was never isolated in pure culture
X-ray analyses highlighted the effect of redox conditions on different types of Poly-P: the polymers associated with Mg and K are more metabolized than the ones associated with Ca, which means that this latter type of phosphate storage is not influenced by the presence or absence of aerobic conditions [20]

Summary

Introduction

Phosphorus is an essential element required for food production. It has been estimated that about. The global growing population induces a progressive increase of fertilizers’ requirement, which means an increasing need for phosphate (P). In this context, the establishment of circular economy applicable to P resources appears obvious [1]. The remaining percentage mainly belongs to China and the USA This geopolitical context can generate unexpected increases of fertilizers’ prices, which occurred in 2008 [2]. Sewage sludge resulting from wastewater treatment contains significant quantities of P. This is due to the presence of phosphate. PAOs have been studied in many research papers Under specific conditions, these microorganisms can store P as polyphosphate (Poly-P). It presents an inventory of analytical techniques which can be used to detect the presence of PAOs and Poly-P

Techniques for the Isolation of PAOs

Isolation of PAOs

Anaerobic

Poly-P

Extraction procedures and phosphate

Conclusions