Phosphorus is a vital component for agriculture. Phosphorus current sources are limited and will be exhausted in a few dozen years. Thus, phosphorus recycling for agricultural use is therefore imperative. On the other hand, the presence of phosphorus in wastewater is an environmental problem of increasing dimensions, mainly due to the eutrophication of water bodies. The aim of this project is to simultaneously solve two environmental problems: 1) phosphate extraction from wastewater thus preventing eutrophication of effluents; and 2) to provide a renewable source of phosphorus that could be used as an agricultural fertilizer. To achieve this aim we will construct a genetically modified bacteria able to take up large amounts of phosphate and accumulate it in the form of polyphosphate.

Phosphorus is a vital component for all living beings, but with low availability in nature. It can be found primarily in the form of orthophosphate (Pi). Bacteria carry several genes related to uptake and assimilation of Pi.

In Escherichia coli, Pseudomonas aeruginosa, Chromobacterium violaceum, to mention three bacterial species investigated in our lab, there are at least two of Pi transport systems – PitA and Pst. Pst is encoded by a five-genes operon. The first four genes encode proteins involved in Pi transport, while the last gene of the operon, phoU, encodes a protein which exact function is unknown. phoU mutants accumulate vast amounts of polyphosphate (polyP), and are more sensitive to antibiotics and environmental stresses.

PolyP is a polymer consisting of tens or hundreds of Pi molecules connected by high-energy chemical bonds. polyP is present in all living beings, including humans, where it has various functions, from phosphate and energy storage to participation in the process of blood coagulation in mammals.

In this project, we study what governs the accumulation of polyP in bacteria, particularly the mechanism through which the phoU mutation cause the large accumulation of polyP in P. aeruginosa.