Original paper

Primary productivity and photoacclimation in cyanobacteria a comparison of carbon fixation, oxygen evolution and in vivo fluorescence

Müller, Brigitte; Schagerl, Michael


The relation between carbon uptake assessed by the radiocarbon technique, oxygen evolution measured with an oxygen electrode and photosystem II electron transport rates estimated by means of pulse amplitude modulated fluorescence technique was investigated for four filamentous cyanobacteria strains. The results indicate that a direct conversion of fluorescence measurements into production rates is still problematic, since phycobilins contribute significantly to the fluorescence signals and state transitions between the photosystems affect the results, too. Moreover radiocarbon incorporation rates can be influenced artificially by bottle effects, especially at high irradiances, where photoinhibition and Mehler reaction occur. In this study, also photoacclimation at two different light intensities was investigated by means of chlorophyll a and biomass specific photosynthesis-irradiance characteristics. Among the examined species two different strategies were observed. Both strategies resulted in higher chlorophyll a and ash-free dry mass specific α-slopes of low light adapted cells. The main difference lies in the variation of the maximal photosynthetic capacity between high and low light adapted cells.


carbon fixationcell volumecyanobacteriapam fluorescencep-i curvephotoacclimation