Amino Acids as Nitrogen Sources for the Growth of Euglena gracilis and Astasia longa

SYNOPSIS. Euglena gracilis (bacillaris variety, strain SM‐L1, streptomycin‐bleached) used the following amino adds (10−3 M) as sole nitrogen source for growth on a defined medium: glycine, alanine, valine, leucine, isoleucine, serine, threonine, and glutamic acid. Aspartic acid was used at 10−2 M. Glutamine and asparagine were used at 10−3 M and were better N sources than their parent dicarboxylic amino acids. Not used as sole N source for growth were phenylalanine, tyrosine, tryptophan, cysteine, cystine, methionine, proline, hydroxyproline, histidine, arginine, lysine, and taurine. Astasia longa (Jahn strain) was more restricted than Euglena and used only asparagine and glutamine as N sources for growth.