Utilization of Fe3+ by the inshore colorless marine dinoflagellate Crypthecodinium cohnii

A Puerto Rican isolate of the colorless dinoflagellate Crypthecodinium cohnii was grown in a defined marine medium. Fe was added as Fe(NH4)2(SO3)2 - 6H2O (2.0 mg%), FeCl3 - 6H2O (1.0 mg%) or a particulate slurry prepared from FeCl3 + KOH, along with varying concentrations of several chelators. Heavy growth at pH 7.5-7.7 occurred with salicylhydroxamic acid, aurintricarboxylic acid, EDTA, NTA, and humic acid; and at pH 7.9-8.1 with SHAM and ATA. Moderate growth occurred at pH 7.5-7.7 with sulfosalicylic acid, dipicolinic acid, pyrocatecholdisulfonic acid, hexanohydroxamic acid, L-histidine, and at pH 7.9-8.1 with 1-naphthohydroxamic acid, EDTA, NTA. Slight growth occurred at pH 7.5-7.7 with benzohydroxamic acid, 1-naphohydroxamic acid, 2.6-dipicolinic acid N-oxide, salicylic acid, rhodotorulic acid, Na oxalate, EDDHA, sorbohydroxamic acid, gamma-pyrone-2, 6-decarboxylic acid, and at pH 7.9-8.1 with hexanohydroxamic acid, benzohydroxamic acid. Some ecological and physiological implications are discussed.