MISCELLANEOUS ACIDS, METABOLIC PRODUCTS, PIGMENTS 229 



academic interest only, but the future may find useful functions for 

 some of them. 



That filamentous fungi growing in synthetic media with sugar 

 synthesize amino acids is self-evident since the cell material must 

 contain proteins. Contrary to the much quoted opinion of Abder- 

 halden, cyclic amino acids are among those synthesized, and proline, 

 phenylalanine, tryptophan, and tyrosine have been definitely identi- 

 fied. Indeed all the proteins essential for animal growth are present 

 in a number of molds. Skinner and IMuller ^^ have grown molds on 

 media consisting of inorganic salts and sugar and fed the mold as 

 the sole source of protein to weanling rats. Although the rate of 

 growth was slow it was definite. The limiting amino acid in all cases 

 was methionine (or cystine). With the addition of one or the other 

 of these amino acids the rate of growth of the animals M^as very much 

 enhanced. The female animals were raised to maturity and they 

 produced litters of young with no other protein food than mold 

 mycelium plus cystine. This synthetic ability of molds w^as utilized 

 in World War I according to Pringsheim and Lichtenstein.^^ Straw 

 was inoculated with a species of Aspergillus and ammonium salts 

 were added. This material was fed to cattle after the inorganic 

 nitrogen was transformed to mold proteins. 



Because of the high fat content of the mold mycelium, studies have 

 been carried out to investigate the production of fats by molds. As 

 much as 41.5 per cent of the mold mycelium may consist of fat ac- 

 cording to Ward, Lockwood, May, and Herrick."'' Most of the in- 

 vestigations have been carried out by cultivating the fungi on salt- 

 glucose media. See Prescott and Dunn-** for a discussion of the 

 production of fats by molds. 



The mycelium and spores of the various fungi are often brightly 

 colored. Some of the pigments .liave been isolated and studied. 

 Prescott and Dunn suggest the possibility that molds may be used 

 commercially in the production of dyestuffs. The Chinese have long 

 used Monascus purpureus, which produces a red pigment, in coloring 

 rice, "Ang-quac," "wines," and sauces. The mold mycelium develops 

 through the rice, giving it a friable texture and coloring the entire 

 mass red or purple, or shades in between, depending upon the pH. 

 This mold is also the cause of red silage, forming red masses up to 

 one-third meter in diameter. Table 3 (pages 240 to 247) is an 

 adaptation of a compilation by Porter *^ of some of the pigments 

 produced by molds. Here also the nomenclature is that of Porter, 



