The dynamics of the intracellular contents of carbon, nitrogen, and chlorophyll a under conditions of batch growth of the diatom Phaeodactylum tricornutum (Bohlin, 1897) at different light intensities

Abstract

It was found that during batch growth of the diatom Phaeodactylum tricornutum (Bohlin, 1897) the specific content of nitrogen in the cells (relative to carbon) decreased with decreasing nitrogen concentration in the medium below ∼10 µM/L. When the nitrogen of the medium was exhausted, the microalga continued their growth for some time using the cell reserve of this element. The C/N ratio in cells increased from 5 to 14 and the density of the culture (relative to carbon) increased by approximately twofold. The correlation between the specific-growth rate of P. tricornutum and the C/N ratio in the cells was described by an equation similar to the Droop (1968) model. The ratio of the intracellular concentrations of carbon and chlorophyll a (C/Chl a), while reducing the specific nitrogen in the cells, increased exponentially; this effect increased with increasing light intensity. The value of the minimum cell quota for nitrogen did not depend on the light condition of culture growth.