[Investigation of the relation between extracellular excretion of glycollate and the photosynthetic CO2-uptake in the blue-green alga Anacystis nidulans].

The formations of transients in CO2 exchange in the blue-green alga Anacystic nidulans is dependent on the temperature used during the measurements. The algae were grown in a low light intensity (4000 lux) under normal air conditions and measured in the same low CO2 concentration (0.03 vol. %) but under a higher light intensity (10 000 lux). At a temperature of +20°C the stationary rate of CO2 uptake was reached directly. At a temperature of +35°C, on the other hand, a maximum of CO2 uptake could be observed at the beginning of the light period followed by a steady rate of photosynthesis, which was higher than at +20°C. In the beginning of the dark period a CO2 outburst appeared at 35°C.Only at a low temperature (+20°C) did we find a light induced glycollate excretion; after a maximum at 7 1/2 minutes illumination the release of glycollate ceases and the level decreases to a lower value. A similar time course exists during illumination in red light (621 nm, 1.5·10(-8) einsteins) and a temperature of +20°C. In blue light (432 nm, 1,5·10(-8) einsteins, +20°C) and in white light at a high temperature (+35°C) we could not find any light induced glycollate excretion. Our results are discussed in reference to the photorespiration. We explain the formation of transients in CO2 uptake of Anacystis at a high temperature (+35°C) and in blue light (+20°C) on the basis of the influence of photorespiration.