Phosphatase activity of the blue-green alga (cyanobacterium) Nostoc commune UTEX 584

Abstract

Abstract Nostoc commune UTEX 584 was observed to grow on a range of organic phosphate sources, indicating the possession of phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities, but it was unable to utilize phytic acid. The use of ρ-nitrophenyl phosphate (ρNPP) as substrate showed the presence of cell-bound and extracellular PMEase. Cell-bound PMEase and PDEase were detected during growth in batch cultures, when the mean cellular phosphate content fell to 0.76% algal dry weight. Use of bis-ρ-nitrophenyl phosphate (bis-ρNPP) showed that cell-bound PDEase activity (measured as ρ-nitrophenol released) was about half that of PMEase, but that no extracellular PDEase activity was present. PMEase and PDEase activities both decreased when the cellular phosphate content fell below 0.3%. The optimum temperatures for PMEase and PDEase activity at pH 7.6 were 32°C and 42°C, respectively; the optima were lower when the assay was performed at pH 10.3. The pH optima for PMEase and PDEase differed sligh...