LONG-TERM ACCLIMATIZATION OF SCENEDESMUS-BICELLULARIS TO HIGH-FREQUENCY INTERMITTENT LIGHTING (100 HZ) .2. PHOTOSYNTHETIC PIGMENTS, CARBOXYLATING ENZYMES AND BIOCHEMICAL-COMPOSITION

The long-term responses of the green microalga, Scenedesmus bicellular is, to a 100 Hz quasi-square wave (intermittent light, IL) were assess ed after a 4 week acclimatization period. At the end of this period, t he photosynthetic pigments, carboxylating enzyme activities and bioche mical composition of algae grown under IL were compared to those of al gae acclimatized to a light flux without fluctuations (continuous ligh t, CL). Differences between IL and CL treatments were small. IL cells grown under limiting irradiance had characteristics close to CL cells grown at the same daily irradiance. At saturating irradiance, the char acteristics of IL cells resembled those of CL cells at the same instan taneous irradiance, mostly because of the flattened response of microa lgae to increased irradiance. The flickering of any artificial lightin g system (100-120 Hz) can thus be neglected when such light is used to grow algae.