Phosphorus uptake by immobilized cells of the alkali-tolerant cyanobacterium oscillatoria amphibia ag. ex gomont

Abstract

The phosphorus removal potential of the bloom-forming, alkali-tolerant cyanobacterium Oscillatoria amphibia was studied by entrapping and immobilizing it in calcium alginate. The uptake kinetics for orthophosphate-phosphorus (PO₄-P) were determined by growing O. amphibia in Jaworski medium (pH 9) in 14.6 Wm^-2 light intensity at 24±1°C. The pH of the culture medium increased to 11.0 during growth. This facilitated the maintenance of unialgal cultures in the absence of any contaminants. Immobilized filaments showed potential capability of phosphorus accumulation. A stocking biomass of 0.4 µg chl a bead^-1 at external pH 9 was found to be suitable for rapid phosphorus removal. Phosphorus uptake kinetics of immobilized filaments were also dependent on the initial phosphorus concentration. These findings may be useful for designing a bioreactor to optimize phosphorus removal using an immobilized cyanobacterial system.