130 



PHYSIOLOGY OF THE FUNGI 



as the alcohol; (3) the stereochemical nature of the glycoside linkage; (4) 

 the carbon of the alcohol moiety which forms the glycoside linkage; and 

 (5) the ring structure of the component sugars (see Oilman, 1943), 



Maltose. It is doubtful whether this disaccharide occurs free in 

 nature. It is formed when starch is enzymatically hydrolyzed; on 

 further hydrolysis two molecules of glucose are formed. This disac- 

 charide is utilized by many fungi. The glycoside linkage is alpha in 

 maltose. 



H OH 



C 



H-C-OH 



I 

 HO-C-H 



I 

 H-C-0 



I 

 H-C-0 



I 



CH2OH 



Maltose 



Cellobiose. The occurrence of this sugar as a repeating unit in cellu- 

 lose makes it important. Cellobiose differs from maltose only in the 

 nature of the glycoside linkage. With few exceptions only fungi which 

 produce enzymes which attack the /3-glycoside linkage will utilize this 

 sugar. 



HO-C-H 



CH2OH 



CH2OH 



Cellobiose 



Since cellobiose and maltose differ only in the nature of the glycoside 

 linkage, it would be interesting to compare the utilization of these two 

 sugars by a large number of fungi. Cellobiose has been studied so infre- 

 quently that the necessary data are lacking. 



