ORGANIC NUTRIENTS OF FUNGI 21 



may, for example, CH 3 CHOH-, =CHCOH=, CH 3 CO-, 

 CHoOH-CHo — , be split off in degradation. 



The relationship of molecular configuration of sugars to utili- 

 zation in amino acid formation by Aspergillus niger has been 

 elucidated by Steinberg (1942). This fungus was found to use 

 all pentoses and hexoses having an /- 3 -carbon atom and a rf-4-car- 

 bon atom except the epimers of d- xylose. 



Attention has been called by Steinberg (1939a, 1939b) to an- 

 other factor that must be considered in tests to determine the as- 

 similability of a given carbon compound. When A. niger was 

 grown in the presence of lactose, galactose, glycerol, or mannitol 

 alone, the yields were 75, 28, 350, or 34 mg, respectively. When 

 the carbon source consisted of a mixture of mannitol and lactose, 

 the yield was 234 mg; of mannitol and galactose, 393 mg; of gly- 

 cerol and lactose, 458 mg; of glycerol and galactose, 155 mg; of 

 mannitol and glycerol, 545 mg; and of lactose and galactose, 17 mg. 

 Steinberg interpreted these improved yields from mixtures to 

 better proportion of molecular groups. 



An introduction to the information concerning the use of fats 

 and oils as sources of carbon may be secured from reports of 

 Tausson (1928) and Hopkins and Chibnall (1932). Tausson 

 found that Aspergillus flaviis consumes olive oil, cocoa butter, 

 beeswax, tripalmitin, and higher paraffins. His data show that 

 591.4 mg of paraffin was utilized in 35 days and that 289.1 mg of 

 mycelial mat was formed as a result. Hopkins and Chibnall found 

 that the higher paraffins with chains not exceeding C 34 H T o were 

 assimilable by A. versicolor. In the breakdown of these substances 

 evidence indicates that ketones first arise and on further oxidation 

 yield fatty acids. Among other vegetable oils that have been 

 found to be consumed by molds arc linseed oil and walnut oil. 



Nitrogen requirements. The numerous studies that have 

 dealt with the nitrogen requirements of fungi have been primarily 

 directed toward finding;- the most suitable sources of nitrogen. 

 The results of this work until 1930 were largely summarized by 

 Czapek (1930). Later Robbins (1937) classified fungi into four 

 groups on the basis of the form of nitrogen they are capable of 

 assimilating. One group utilizes organic nitrogen alone; the sec- 

 ond, both organic nitrogen and ammonia; the third, not only or- 

 ganic nitrogen and ammonia but also nitrate nitrogen. The fourth 

 "group is capable of fixing elemental nitrogen and can also utilize 



