The Amino Acid Composition of Microorganisms

Despite the extensive data that has accumulated on the chemical composition of microbial cells, information concerning microbial proteins, which are of major importance among cellular constituents, is fragmentary and, in part, inaccurate. This has been due primarily to inadequate and unreliable analytical methods for the determination of the basic protein units, the amino acids. The literature to 1926 on the amino acids in bacteria, yeasts, and fungi has been reviewed by Bu-chanan and Fulmer (1928). More recent papers which deal primarily with the amino acids of various species of Azotobacter are cited by Camien, Salle, and Dunn (1945). Similar information on marine and fresh-water algae is also available (Mazur and Clarke, 1938, 1942) as well as more recent data on yeasts (Sagara, 1930; Fink and Just, 1942; Block and Bolling, 1945). In addition to recording some of the types and approximate quantities of amino acids in various microorganisms, early investigators attempted to determine whether the amino acid composition of a particular organism is constant or varies with environmental conditions, especially with the composition of the medium.