Kinetics of nitrogen- or phosphorus-limited growth and effects of growth conditions on nutrient uptake inChattonella antiqua

摘要

Chattonella antiqua was grown in a nitrogen- or phosphorus-limited semicontinuous culture system. Using the cells in steady growth state, the relationship between growth rate and cell quota and effects of growth conditions on nitrate, ammonium and phosphate uptake were examined. Under nitrogen-limited conditions, growth rate as a function of nitrogen cell quota followed the empirical Droop equation and the uptake of nitrate and ammonium was not significantly affected by growth rate. Similarly, under phosphorus-limited conditions, the growth rate as a function of phosphorus cell quota also followed the Droop equation and phosphate uptake was not significantly affected by growth rate.Combining the results obtained in the present study with those from previous studies on nutrient uptake, half saturation constants for growth (Kg) were calculated for nitrate, ammonium and phosphate. Comparisons ofKg with nutrient concentrations in the Seto Inland Sea in summer, where red tides ofC. antiqua often occur, suggest that phosphate is one of the controlling factors for the population ofC. antiqua.