Effects of aluminum and fluoride on phosphorus acquisition by Chlamydomonas reinhardtii

Al (10 μM) and F (50 μM) added singly or in combination have no effect on growth of Chlamydomonas reinhardtii in acid or alkaline media containing organic or inorganic P. Cell surface phosphatase activity, however, is increased in glucose-1-phosphate-amended cultures exposed to Al, but only at low pH. This result is an indirect effect caused by Al binding to the organic P, which inhibits organic P utilization and induces phosphatase synthesis in C. reinhardtii as a compensatory response. Phosphatase activity is inversely correlated with lake pH, suggesting that such a mechanism may operate in nature. Al thus appears to enhance phosphatase activity in acidified waters by impeding dissolved organic P catabolism.