PIGMENTS OF FUNGI 83 



AMINO ACIDS 



Apparently many fungi are able to synthesize their amino acids 

 from inorganic nitrogen. Such synthesis may not be sufficiently 

 rapid, however, for optimum growth, as is indicated bv the fact 

 that more rapid growth occurs after amino acids are added to the 

 substrate. 



Steinberg (1942) studied the utilization of amino acids as carbon 

 and nitrogen sources for Aspergillus niger and interpreted his ex- 

 periments as showing that amino acids may be formed from and 

 reconverted to sugars. A mixture of proline, glutamic acid, and 

 ornithine provided carbon and nitrogen almost as satisfactorily 

 as did sucrose and ammonium salts. 



Biogenesis of specific amino acids, as of arginine and trytophane, 

 especially by Neurospora crassa, has been given consideration 

 [Tatum (1944)]. From such investigations the accumulated evi- 

 dence indicates that the formation of primary amino acids in- 

 volves oxidation of the a-hydroxy acid and amination of the keto 

 acid. 



PIGMENTS OF FUNGI 



To almost any question regarding the pigments of fun^i the 

 mycologist makes the embarrassed answer, "I don't know." iMany 

 species are beautifully pigmented, and use is made of this fact 

 in classification. Almost surely pigments serve some essential 

 function in the metabolic activities of fungi, presumably in respi- 

 ration, but this field of physiology remains quite wholly unex- 

 plored. To date the studies on such pigments deal mainly with 

 their chemical nature. 



Citromycetin and citrinin. These two pigments were iso- 

 lated by Raistrick and his associates (1931), citromycetin being 

 obtained from Pemcillium glabrum and citrinin from P. citrinum. 

 The organisms were grown on modified Czapek-Dox medium 

 (NaNO s , 2 grams; KH,P0 4 , 1 gram; KC1, 0.5 gram; MgSCV 

 7H 2 0, 0.5 gram; FeS0 4 -7H 2 0, 0.02 gram; water, 1 liter; glucose, 

 50 grams). From P. glabrum Hetherington and Raistrick [Rai- 

 strick (1931)] extracted in 50% alcohol a substance that crystal- 

 lized into lemon-yellow needle crystals, citromycetin, which is 

 intensely olive green with ferric chloride. The reactions of this 



