The Production of Extracellular Carbohydrates by Some Marine Flagellates1

Extracellular carbohydrate production during the growth of bacteria‐free cultures of the marine flagellates Isochrysis galbana, Monochrysis lutheri, Prymnesium parvum, Dunaliella euchlora, Pyraminomonas sp., Rhodomonas (?) sp., and Chlamydomonas sp. was followed by the N‐ethyl carbazole method. Carbohydrate production did not parallel cell numbers during exponential growth of any of these organisms; maximum concentrations during this phase were under 3 mg/L. Carbohydrates accumulated in all stationary cultures (having 10 6 –10 7 cells/ml), to the greatest extent in Prymnesium cultures, which attained 123 mg/L. Isochrysis and Monochrysis produced 25 and 16 mg/L, respectively, while the others had under 10 mg/L even when cell disintegration was evident. Aging cultures (not all bacteria‐free) of 4 diatoms, 2 dinoflagellates, 2 additional green algae, and a cyanophyte were assayed. Concentrations ranged from 1.5 to 60 mg/L. This suggests that the organisms studied contribute significant free carbohydrates only during late bloom conditions, when algae are abundant and under physiological circumstances resembling stationary or declining culture.