Nutritional Characteristics of Some Chrysomonads 117 



chelator alone or of chelated trace-metal mixtures (which are 

 over-chelated) for Hymenomonas may denote a preference for 

 the solubized form. Obviously, reliable data on trace metal re- 

 quirements and concentrations can only be had by virtual elim- 

 ination of them (2). 



HETEROTROPHIC ABILITIES 



Phosphorus and Nitrogen 



As for most of the algae tested so far, the aforementioned 

 chrysomonads utilize besides inorganic phosphate, glycerophos- 

 phoric, adenylic, guanylic, and cytidylic acids. 



Single amino acids and amino acid mixtures and single 

 amines were tested in concentrations ranging from 1-10 mg %; for 

 the utilized N- sources additional concentrations ( up to 50-70 mg 

 %) were also tried. Amines were tested because Gijrodinium coh- 

 nii utilized betaine and because many marine invertebrates and 

 bacteria produce amines and it is not unlikely that amines would 

 be present in seawater. Hymenomonas and Syracospliaera util- 

 ized the widest range of organic nitrogen. Hymenomonas utilized 

 best glutamate, aspartate, alanine, arginine, and lysine; leucine, 

 methionine, tyrosine, ornithine, citrulline, canavanine, and y- 

 aminobutyric acid are also utilized but less well. Syvacosphaera 

 utilized best aspartate, tryptophan, arginine, and lysine; alanine, 

 glutamate, canavanine, ornithine, citrulline and y-aminobutyric 

 acid are less utilized. Ochrosphaera utilized only arginine, taiu-ine, 

 ornithine, citrulline, and agmatine. C huxleyi utilized a mixture 

 of histidine, arginine and lysine; each one of the components is 

 less utilized than a combination of the three amino acids. Pavlova 

 does not utilize any of the organic sources tried. Urea was tried 

 but at very low levels (0.01-1 mg %); only Syracosphaera seemed 

 to utilize urea as well as nitrate; Hymenomonas and Pavlova 

 showed some utilization at the highest concentration tried (1 

 mg%). 



Nitrate was the best inorganic N- source; maximum growth 

 was obtained in the 10-50 mg % range. Only Hymenomonas 

 utilized better the amino N of glutamate, aspartate and alanine 

 than the N of nitrate (based on ratio optical densities: weight 

 of N}. The utilization of the organic N sources for the other 



