The effect of salt concentration (NaCl) on
growth, fluorescence, photosynthetic activities and
pigment content of the cyanobacterium Arthrospira
platensis has been investigated over 15 days. It has
been observed that high NaCl concentration induces
an increase of the growth, photosynthetic efficiency
(α), phycobilin/chlorophyll ratio and a slight decrease
of dark respiration and compensation points. Moreover,
high NaCl concentration enhances photosystem
II (PSII) activity compared to photosystem I (PSI).
Results show that the phycobilin-PSII energy transfer
compared to the chlorophyll-PSII (F695,600/F695,440)
increases. However, data obtained about the maximal
efficiency of PSII photochemistry are controversial.
Indeed, the Fv/Fm ratio decreases in salt adapted
cultures, while at the same time the trapping flux per
PSII reaction center (TR0/RC) and the probability of