New Optical Approaches in Studying Photophysiological Parameters of Cyanobacteria in situ

Kuzminov F. I., Shirshin E. A., Gorbunov M. Yu., Fadeev V. V.

In this work we examine new approaches for measurment of photophysical and photophysiological parameters of photosynthetic organisms that could be used to assess their physiological state, photosynthetic efficiency, and primary productivity. On the example of cyanobacteria, we demonstrate the potential of Fluorescence Induction and Relaxation technique (FIRe) and Non-linear Laser Fluorimetry (NLF) in assessing physiological state of phytoplankton. We apply these methods to study mechanism of high light tolerance (non-photochemical quenching). In particular, we show that chlorophyll-containing light harvesting complex of cyanobacteria does not directly participate in the mechanism of non-photochemical quenching. Studies on the effect of spectral properties on the physiological state of cyanobacteria demonstrate that light induced changes in the content, quantity and ratio of chlorophyll- and phycobilin-containing light harvesting complexes could be determined from measured photophysiological parameters. Thus, FIRe and NLF could be used to assess light growth conditions in situ.

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