PHOTOSYNTHESIS IN ALGAE: I. ACCUMULATION PRODUCTS IN THE RHODOPHYCEAE

Abstract

Photosynthesis in14CO2was observed in 12 algal species from six rhodophycean orders. Rates of CO2uptake ranged from 0.5 to 4.0 mg h−1 × g−1on a fresh weight basis. Excretion of new photosynthate was not important in macrophytes whereas 4.4% of the14C fixed by Porphyridium sp. was excreted in 2 hours.Members of the Ceramiales could be distinguished by their relatively large accumulation of14C in the alcohol-insoluble fraction.In most species, alanine, glutamic and aspartic acids, serine, and glycine were the most radioactive soluble amino acids. The chief soluble radioactive carbohydrate was floridoside except in the Ceramiales, in which it was low or absent. Batrachospermum, which contained14C-trehalose, also lacked floridoside.14C-Mannitol was recorded in nine species and14C-glucose in two others. Several unknown substances were detected on chromatograms.