Photosynthetic activity in synchronized cultures of algae and its dependence on light intensity

Summary Photosynthetic capacity at several levels of illuminance was investigated in cells of the successive developmental stages of the high temperature strain, Chlorella 7-11-05. The saturating light intensity, rates of photosynthesis at light saturation and at half-saturation, and the slope of the light dependent portion of the light intensity curves were proved to be bound with the developmental status of cells. The effect of the choosing of the basis for calculations of photosynthetic activity — whether packed cell volume, dry weight, nitrogen, or chlorophyll content—was discussed. The fact was stressed that with the available synchronization technique the observable amplitude of changes in metabolic activity in the course of cell development is a minimal one and the actual fluctuations in photosynthetic rates in non-synchronized suspensions in the course of the life cycle of the individual cells are expected to be higher than those recorded for synchronized populations.