Control of alkaline phosphatase activity in Anabaena oryzae Fritsch

Repression and derepression of cellular alkaline phosphatase (APase) produced by Anabaena oryzae Fritsch has been studied in response to changing levels of phosphate (Pi). Phosphate-rich cells having no detectable alkaline phosphatase activity required an incubation period of 15 h in phosphate-free medium to express cellular phosphomonoesterase activity. Activities of cellular phosphodiesterase (PDEase) and extracellular PMEase were expressed later with switch-on times of 20 and 24 h, respectively. Contrary to this, higher levels of phosphate in the culture medium delayed switch-on times for the expression of the enzyme activity. Cells transferred to the inductive medium and incubated in dark showed 77% less activity than that found in cells incubated in light. Similar observations were also made in cultures treated with DCMU, indicating that photoenergy is required for synthesis of phosphatases. The switch-on times for the expression of PMEase are also determined, using specific transcription and translation inhibitors.