CARBON SOURCES 



137 



Table 28. Distribution of Radioactive Carbon (C^O in the Culture Medium 

 AND Mycelium of Rhizopus nigricans Exposed to C^'02 in the Gas Phase for 



30 Minutes 

 Results are expressed as percentage of C^Oo assimilated. (Foster et ah, Proc. 



Natl. Acad. Sci., U.S. 27, 1941.) 



Substance tested 



Total C* in supernatant solution after removing cells. 



Fumaric * acid in this solution 



C* in neutral volatile distillate 



Total C* in acid extract of cells 



Fumaric * acid in this solution 



C* remaining in cells after acid extraction 



Anaerobic 



29.0 

 25.0 

 0.2 

 30.0 

 12.0 

 41.0 



* Designates radioactive carbon. 



It is probable that carbon dioxide enters into various metabolic proc- 

 esses. Foster and Davis (1948) postulate that strains of Rhizopus 

 nigricans which produce fumaric acid anaerobically do so according to 

 scheme IV. Cantino (1949), in studying the metabolism of Blastocladia 



Scheme IV. A Scheme for the Anaerobic Transformation of Glucose into 



Fumaric Acid by Rhizopus nigricans* 



nC6Hi206 



CH3CHOHCOOH 

 Lactic acid 



I 



i 



+2H yf-nAU 



nCHsCOCOOH 



Pyruvic acid 



+ CO2 



HOOCCH2COCOOH 

 Oxalacetic acid 



>- 



■^ CO2+ CH3CHO 

 Acetaldehyde 



+ 2H 



CH3CH2OH 



Ethyl alcohol 



+ 2H 



HOOCCHgCHOHCOOH 

 Malic acid 



I 



* Courtesy of Foster and Davis, Jour. Bad., 56 : 335, 1948, 

 & Wilkins Company. 



-HOH 



HOOCCH-.CHCOOH 

 Fumaric acid 



Published by permission of The Williams 



pringsheimii, found that, by increasing the carbon dioxide in the gaseous 

 phase, the formation of lactic acid was decreased, while the amount of 



