96 PHYSIOLOGY OF THE FUNGI 



phosphate by A. niger takes place only in the presence of oxygen. The 

 utilization of phosphorus by yeasts, and presumably by other fungi which 

 are capable of anaerobic respiration, may take place in the absence of 

 oxygen. Various respiratory inhibitors such as iodoacetate, azide, and 

 cyanide inhibited both respiration and phosphorus metabolism. This 

 points to an intimate connection between carbohydrate and phosphorus 

 metabolism. By analysis, ortho-, meta-, and pyrophosphates were 

 found in the mycelium. Since only orthophosphate was supplied in the 

 medium, it is shown that A. niger is capable of these transformations. 



Phosphorus appears to participate in almost every step in the anaerobic 

 dissimilation of glucose into alcohol by yeast. Some of these steps may 

 be common to other fungi. It is remarkable that the formation of alcohol 

 by yeast and lactic acid in muscle should follow almost the same pathways. 

 Phosphorus is required in the enzymatic transformation of glucose into 

 alcohol and carbon dioxide (Harden, 1932). Sumner and Somers (1947) 

 and Tauber (1949) have summarized the enzymatic reactions involved. 



Either starch or glycogen may be transformed into glucose-1-phosphate 

 by enzymatic esterification. The shift of the phosphate radical to the 

 other end of the glucose molecules leads to glucose-6-phosphate, which 

 may also be formed by direct esterification of glucose. Glucose-6-phos- 

 phate is transformed into fructose-6-phosphate and then into fructose- 

 1,6-diphosphate. Scission of a molecule of fructose-l,6-diphosphate 

 yields dihydroxyacetone-1-phosphate and D-1-phosphoglyceric aldehyde. 

 An equally long series of transformations leads to pyruvic acid, 

 CHs — CO — COOH, Avhich on decarboxylation by the enzyme carboxylase 

 yields acetaldehyde, which is enzymatically reduced by DPN-H2 to ethyl 

 alcohol. Cocarboxylase and diphosphopyridine nucleotide (DPN) are 

 coenzymes, both of which contain phosphorus. 



Gould et al. (1942) studied the formation of alcohol by Fusarnim 

 tricothecioides and found the limited production of alcohol by this species 

 was due to insufficient synthesis of diphosphopyridine nucleotide. Alco- 

 hol production was increased 20- to 25-fold by the addition of either yeast 

 extract or DPN to the medium. The paper of Semeniuk (1943-1944), 

 which deals with the relation of phosphorus to glucose dissimilation by 

 Chaetomium funicola, has an extensive bibliography (117 references). 

 Nord and Mull (1945) have summarized a long series of papers on the 

 physiology and biochemistry of Fusarium lini and reached the conclusion 

 that fermentation by this fungus follows a pathway which does not 

 involve the sugar phosphates. The review of Barron (1943) on the 

 mechanisms of carbohydrate metabolisms contains much information 

 about the role of phosphorus (219 references) in carbohydrate metabo- 

 lism. The role of phosphorus compounds in the transfer of energy was 

 noted in Chap. 4. 



