TEMPERATURE-DEPENDENCE OF THE O-2-OSCILLATION PATTERN IN THE FILAMENTOUS CYANOBACTERIUM OSCILLATORIA-CHALYBEA AND IN CHLORELLA-KESSLERI

Five characteristic discontinuities of the pattern of oxygen evolution have been detected for the filamentous cyanobacterium Oscillatoria ch alybea in the temperature range of 0 degrees C to 30 degrees C. The te mperatures at which these discontinuities occur are: approximate to 5 degrees C, approximate to 11 degrees C, approximate to 15 degrees C, a pproximate to 21 degrees C and approximate to 25 degrees C. The calcul ated initial 5-S state distribution, the miss parameter and the fracti on of the fast transition S-3 --> S-0 + O-2 are affected. The disconti nuities are observed at the same transition temperature also for Chlor ella kessleri hence are not specific for the cyanobacterium. Based on these studies it is concluded that the not vanishing oxygen signal und er the first flash of a flash train in Oscillatoria cannot have its or igin in interactions between oxygen-evolving complexes. A decrease of temperature should slow down the expected charge exchanges, improve th e oscillations, thus reduce or lower the first two oxygen amplitudes o f the oscillatoria pattern. Lowering of the temperatures improves the oscillations but does not lower the first O-2 signal of the pattern.