Long-term acclimatization of Scenedesmus bicellularis to high-frequency intermittent lighting (100 Hz). II. Photosynthetic pigments, carboxylating enzymes and biochemical composition

The long-term responses of the green microalga, Scenedesmusbicellularis, to a 100 Hz quasi-square wave (intermittent light,IL) were assessed after a 4 week acclimatization period. Atthe end of this period, the photosynthetic pigments, carboxylatingenzyme activities and biochemical composition of algae grownunder IL were compared to those of algae acclimatized to a lightflux without fluctuations (continuous light, CL). Differencesbetween IL and CL treatments were small. IL cells grown underlimiting irradiance had characteristics close to CL cells grownat the same daily irradiance. At saturating irradiance, thecharacteristics of IL cells resembled those of CL cells at thesame instantaneous irradiance, mostly because of the flattenedresponse of microalgae to increased irradiance. The flickeringof any artificial lighting system (100–120 Hz) can thusbe neglected when such light is used to grow algae.