Effect of photon fluence rate, nitrogen limitation and nitrogen recovery on the level of phycoerythrin in the unicellular alga, Rhodosorus marinus (Rhodophyceae)

Studies were carried out on the effects of irradiance and nitrogen sources on phycoerythrin accumulation in the unicellular Rhodophycea. Rhodosorus marinus. The abilily of this microalgal species for natural cell aggregation was used to separate easily the biomass from the culture medium. Alter the removal of nitrogen from the growth medium, phycoerythrin content decreased with time, faster the higher the fluence rate. The results suggest that, in R. marinua. a large part of the phycoerythrin content of N‐sufficient cells is used for nitrogen storage. Restoration of nitrogen in the growth medium induced an increase of phycoerythrin content. even when cells were maintained in darkness. Different inorganic and organic nitrogen sources were shown to promote also phycoerythrin recovery in the dark.