Uptake and Accumulation of Phosphate by a Marine Diatom Chaetoceros gracilis

摘要

A phosphorus recovery system from various wastes with micro algae is useful for a sustainable use of them. We have previously reported that a marine diatom Chaetoceros gracilis rapidly incorporated inorganic monophosphoric acid in culture medium and accumulated them as polyphosphoric acid during early stage of growth. In the present study, in order to understand the mechanism involved in the phosphoric acid uptake by diatom cells, we analyze the capacity of phosphoric acid incorporation with the culture medium containing different concentration of phosphoric acid. When diatom cells depleted of cellular phosphorus stock were inoculated in a new medium, they incorporated rapidly phosphoric acid in culture medium without proliferation on the first day. The incorporation rate was 10.2 ng and 14.7 ng P/104 cells/day, in a culture medium containing 0.772 and 3.523 mg P/L of phosphoric acid, respectively. The incorporation rate reached maximum on the first day in the culture medium containing 0.772 mg P/L. On the other hand, the incorporation rate increased for two days in the culture medium containing 3.523 mg P/L. Experimental results suggests that phosphorus stock made in the early stage of growth will be a source of organic phosphorus during subsequent growth.