132 



PHYSIOLOGY OF THE FUNGI 



glycoside linkage. Tamiya (1932) reported that Aspergillus oryzae 

 utilized trehalose and raffinose. The trisaccharide raffinose is obtained 

 as a by-product of beet-sugar manufacture. On complete hydrolysis 

 galactose, glucose, and fructose are formed in equivalent amounts. The 

 structure for raffinose is given below. 



Volkonsky (1934) found raffinose to be utilized readily by Pythmm 

 deharyanum and a species of Sporotrichum. One isolate of Phytophthora 

 parasitica utilized raffinose rapidly, while another isolate utilized this 

 sugar slowly. Phytophthora cactorum and P. palmivora utilized this 

 sugar slowly. The great majority of fungi tested by Volkonsky did not 

 utilize raffinose. 



CH2OH 

 O— C 



^ 



HO— C— H 



H— C— OH 



I 

 H— C— O— 



H- 



H— C— OH 



HO— C— H 



I 

 H— C— OH 



H— C— O— 



CHoOH 



D-Fructose 



CH2O- 



D-Glucose 



H— C 



H— C— OH 



I 

 HO— C— H 



I 

 HO— C— H 



H— C— O— 



CH2OH 



u-Galactose 



Raffinose 



Oligosaccharides and polysaccharides are utilized by fewer fungi than 

 is glucose. All microorganisms which can utilize a given polysaccharide 

 are also able to utilize its hydrolytic products (Van Niel, 1944). Not all 

 polysaccharides yield glucose on hydrolysis, but the majority of them do. 



While the evidence at hand does not exclude the direct utilization 

 of disaccharides by some fungi, it is probable that these sugars are 

 hydrolyzed before utilization in most instances. Smith (1949) suggests 

 that Marasmius chordalis attacks cellobiose by a route that involves 

 neither preliminary hydrolysis nor phosphorylation. 



The failure of a fungus to utilize an oligosaccharide may be due either to 

 the lack of the necessary hydrolytic enzyme or to inability to utilize the 

 component sugars. Failure to synthesize the necessary hydrolytic 

 enzymes appears to be by far the most common cause of nonutilization. 

 This is borne out by the data in Table 22. Of the 21 fungi studied by 

 Margolin, two failed to grow on maltose, while eight did not utilize 

 sucrose. Since all these fungi grew well on glucose and fructose, it is 

 evident that failure to utilize maltose and sucrose was due to the fact that 

 these fungi could not hydrolyze these sugars. The nonutilization of 

 lactose by Syncephala strum racemosum is evidently due to the failure of 



