NUTRITIONAL STUDIES OF THE EDIBLE SEAWEED PORPHYRA TENERA. II. NUTRITION OF CONCHOCELIS1

The nutrition of the free-living phase of Conchocelis of P. tenera was studied axenically. Conch-ocelis preferred NO₃, as nitrogen source. Urea and NH₄ in low concentration, asparagine, and lysine were very good N sources. Several other amino acids were also utilized but growth was less abundant. Inorganic and organic phosphates were utilized; they were required at relatively low concentrations. Glycerophosphate gave excellent growth in a comparatively wide range of concentrations (0.1-5 mg P %). The optimal Ca concentration was 10-100 mg %. Needs for boron, manganese, zinc, strontium, rubidium, lithium, and iodine were demonstrated. The iodine effect was remarkable (peak growth with 1μg %); the effective concentration range was very narrow. Iron, cobalt, and bromine seemed to be adequately supplied as impurities of the macro-nutrients. A modified artificial medium (ASP₁₂I) for the Conchocelis phase is presented.