Fat Synthesis in Unicellular Algae Part

Part IV. Nocturnal Effect on Fat Accumulation in Chlorella

Abstract

Participation degree of photosynthesis and respiration in fat synthesis in Chlorella in nitrogen-deficient growth was investigated with the medium of photosynthetic and respiratory quotients. It became clear that photosynthesis is mainly responsible for fat formation at least in the early stage of nitrogen deficiency and the reducing power resulting from light energy can be directly utilized for fat synthesis together with that released from carbohydrate through respiration.
The rate of respiration per unit weight of cell nitrogen showed a remarkable increase with the advance of nitrogen deficiency. This fact strongly suggests that reorganization of nitrogen compounds occurs during the nitrogen-deficient growth.
The effect of dark respiration on the accumulation degree of fat was investigated in relation to the practical nocturnal effect in the outdoor culture for fat production. It was clarified that dark periods give a favourable effect on both growth and fat formation, especially in the growing stage. But it became clear that the amount of fat cannot be increased in a large quantity by converting the accumulated carbohydrate through respiration in a prolonged dark period.