124 



PHYSIOLOGY OF THE FUNGI 



Methylpentoses. D-Isorhamnose, L-fucose, and L-rhamnose are related 

 to D-glucose, L-galactose, and L-mannose in that carbon G with its primary 

 alcohol group in these hexoses has been replaced by a methyl group. 

 These methylpentoses have not been thoroughly investigated in nutri- 

 tional studies involving many fungi. Aspergillus niger utilizes L-rham- 

 nose to some extent, but L-fucose is not utilized (Steinberg, 1942). A. 

 oryzae makes much poorer growth on L-rhamnose than on D-xylose or 



Table 24. Milligrams of IMycelium Produced by Five Fungi Grown upon 



Xylose and Arabinose 

 These sugars were used at concentrations which suppHed 8 g. of carbon per liter. 

 Each 125-ml. flask contained 20 ml. cf medium. Cultures were incubated at 25 °C. 

 (Margolin, thesis, West Virginia University, 1942.) 



Fungus 



Blakeslea trispora 



Mucor ramannianus 



Phycomyces blakesleeanus . . . . 

 Phytophihora erythroseptica . . 

 Pythiomorpha gonapodyoides . 



Days of 

 incubation 



6 

 8 

 7 

 12 

 6 



D-Xylose ' 



77 

 77 

 126 

 15 

 33 



L-Arabinose 



49 

 74 

 85 

 7 

 18 



* This sugar was called Z-xylose in the earlier literature. 



L-arabinose (Tamiya, 1932). Of the five fungi listed in Table 24 only 

 Mucor ramannianus utilizes L-rhamnose (Margolin, 1942). Stereum 

 gausapatum utilizes rhamnose about as well as arabinose (Herrick, 1940), 

 Sugar alcohols. Reduction of the aldehyde or keto group of the 

 simple sugars converts them into alcohols. Several sugar alcohols are 

 widely distributed in nature. Only the formulas for three of the natu- 

 rally occurring sugar alcohols will be given. 



Most fungi appear to utilize the corresponding sugars with greater 

 facility than the sugar alcohols. Data for the comparative growth of 

 five fungi on these sugar alcohols and the parent sugars are given in 

 Table 25. 



