28 NUTRITION OF FUNGI 



ramannianus is able to produce pyrimidine and, if given thiazole, 

 can unite the two to form thiamin. On the nutrient medium de- 

 scribed above, Fusarium niveum, Mucor nrmannictmis, Fythio- 

 morpha gonapodioides, and Rhizopus minus can synthesize their 

 own biotin. Robbins and Ma (1941) observed upon Fusarium 

 avenaceum a beneficial effect of biotin, present in amounts up to 

 1 jug per gram of the agar used. If they employed crystalline 

 biotin (methyl ester, CiiH 18 N L >0 :5 S) stimulation occurred with 

 the addition of as little as 0.001 /xg. 



Graphium ulmi responds in liquid cultures to the presence of 

 pyridoxine (vitamin B, ; ) [Burkholder and McVeigh (1942)]. 

 .Marked increases in dry weight of mycelial mat followed the 

 addition of 50 y of this vitamin per liter of basal mineral solution 

 plus asparaqine and dextrose. On the other hand, this vitamin 

 was found to be unimportant in the growth of Saccharomyces 

 cerevisiae in media supplied with inositol, biotin, and pantothenic 

 acid [Williams, Eakin, and Snell (1940)]. The interaction of 

 biotin, inositol, pyridoxine, pantothenic acid, and thiamin in the 

 <rrowth of yeast has been surveyed in a report by Williams ( 1941 ) . 



Certain amino acids are considered as growth accessory factors 

 in yeast and in various fungi by Nielsen and Sing-Fang (1937). 

 The relationship of vitamin deficiencies to the growth of many 

 specific fungi is treated in a report by Robbins and Kavanaugh 

 (1942). Work of this kind, of course, is dependent largely on 

 the availability of vitamins and the synthesis and commercial pro- 

 duction of some of them. Recently biotin was found to be 

 identical with coenzyme R, and it can now be synthesized [Harris 

 et ah (1943)]. The excellent treatise by Schopfer (1943) sum- 

 marizes the fund of knowledge that has been derived from the 

 researches of vitamins as related to the nutrition of fungi and other 

 plants. 



Studies should also be directed toward determining more about 

 the proximate function of growth factors in the physiology of 

 fungi. Host specificity may be found to be correlated with re- 

 quirements for these factors. Growth factors, if speculation is 

 guided by the developments in recent years regarding their in- 

 fluence on the physiology of animals and of chlorophyll-bearing 

 plants, may be thought to be morphogenic or to regulate repro- 

 duction. 



