18 NUTRITION OF FUNGI 



Diversity in ability to use carbohydrates is indicated by numer- 

 ous reports, but in general the literature shows that glucose is the 

 favorite. It may be removed first from a solution containing a 

 mixture of sugars, or it may even be the only one removed. Su- 

 crose, if present, may be first inverted into dextrose and levulose. 

 If Aspergillus niger is the test organism, Alolliard (1918) found 

 that, when all the dextrose has been utilized, five-sixths of the 

 levulose still remains. 



Attempts to employ the amount of carbon dioxide evolved as 

 the sole measure of utilization of the carbon source may lead to 

 erroneous interpretations, for the reason that some of the products 

 metabolized may be stored within the body of the mold, where 

 they may be oxidized subsequently. Most species give better 

 yields on hexoses than on pentoses, although Hawkins (1915) 

 found that Glomerella cingulata utilizes the two pentoses, arabi- 

 nose and xylose. Weimer and Harter (1921) tested the responses 

 to glucose of Botrytis cinerea, Diplodia tubericola, Fusarium 

 acuminatum, Mucor racemosus, Rhizopus tritici, Sclerotium bata- 

 ticola, and Sphaeronema fimbriatnm, finding that each organism 

 differs in the amount of this sugar required to produce a unit of 

 dry weight. Brannon (1923) found that glucose and fructose 

 are equally acceptable to Aspergillus niger and Fenicilliwn camevi- 

 berti. Fusarium lini } however, is said to be unable to utilize glu- 

 cose [Tochinai (1926)]. 



In a series of studies that may well serve as a model, Raistrick 

 et al. (1931) found that glucose, fructose, and sucrose are excel- 

 lent sources of food for many molds. They evaluated these 

 sugars by keeping "balance sheets" on the amount of sugar 

 utilized and the amount of certain metabolic products formed 

 or of mycelium produced. By means of such techniques differ- 

 ences in the nutritive values of various carbon sources can be 

 determined. Horr's (1936) observations show that both galactose 

 and mannose constitute poor sources of carbon for Aspergillus 

 niger and Fenicilliuvi glaucum. This observation regarding galac- 

 tose is confirmed by Steinberg (1939), who added that lactose 

 supports practically no growth of A. niger, that glycerol results 

 in poor yields, and that dextrose, fructose, sucrose, and /-sorbose 

 are equally effective. 



Variation among species in ability to utilize sources of carbon 

 is further shown by the inability of Achlya prolifera, A. racemosa, 



