Exploration of cyanobacteria as bioremediation candidates to reduce phosphorus contamination

Abstract The aim of this research is to evaluate cyanobacteria as a bioremediation agent for the removal of inorganic phosphate. We have adopted two approaches. The first approach involves the inactivation of the sphU gene in a model cyanobacterium. This gene encodes a negative regulator of the pho-regulon, this regulon includes genes involved in phosphate uptake. Inactivation of sphU results in the constitutive uptake of inorganic phosphate and its accumulation in polyphosphate bodies within cyanobacterial cells. Preliminary data using Synechocystis sp. PCC 6803 has shown that the ΔSphU strain removed 96% of phosphate from the growth medium in 36 h whereas a similar phosphate depletion by wild-type cells took ~72 h. Our second approach involves the screening of native cyanobacteria to identify strains that have optimised their ability to take up phosphate. Our goal is to evaluate suitable cyanobacteria for phosphate uptake. This will be achieved through mesocosm studies designed to assess the ability of the cyanobacteria to selectively remove phosphate with the accompanying generation of biomass with potential to be used as feedstock for various biotechnological applications.