216 



RESPIRATION 



lactate has been shown (84), and carbon- 14 data suggest that a direct 

 reduction occurs (48). Leuconostoc mesenteroides yields the same 

 products as Rhizopus spp., but the mechanism of this heterolactic 

 fermentation is entirely different (75). 



Table 1. The Distribution of Glucose Carbon among the Fermentation 



Products of Rhizopus oryzae* 



* Figures represent millimicrocuries of carbon-14 in each carbon atom. From 

 M. Gibbs and R. Gastel, Arch. Biochem. Biophys. 43: 33-38 (1953), by permission 

 of The Academic Press, Inc. 



Purely enzymatic studies can establish only the possibility of the 

 Embden-Meyerhof pathway, since most of the enzymes of the sequence 

 are also used for disposing of the triose phosphate formed in the 

 phosphogluconate oxidation pathway and since the enzymes, even if 

 present, are not necessarily functional. Pyruvic carboxylase has been 

 detected in several fungi (62, 88, 148, 230, 274). Aspergillus niger 

 extracts contain virtually the complete battery of enzymes necessary 

 for the conversion of glucose to ethanol and carbon dioxide (148); this 

 is consistent with the data cited earlier indicating that some species of 

 Aspergillus produce ethanol. Several of the same enzymes appear in 

 extracts of Penicillium chrysogenum (264) and P. notatum (182). 

 Aldolase, one of the enzymes which is characteristic of the Embden- 

 Meyerhof sequence, is found in Aspergillus spp. (7, 15a, 149, 150), 

 Neurospora crassa (277), Fusarium lini (62), Penicillium spp. (182, 

 264), Streptomyces coelicolor (61), and Tilletia caries (212). 



Ethanol production in Fusarium spp. has already been mentioned. 

 Carbon balance studies, enzymatic analyses, and isotope distribution 

 experiments agree that anaerobically the Embden-Meyerhof pathway 

 is functional and that no other anaerobic mechanism need be postu- 

 lated (62, 125). Balance and fermentation data on Ashbya gossypii 

 also implicate the yeast system (194). 



Streptomyces coelicolor is unable to form either carbon dioxide or 

 acids anaerobically; it contains, however, the enzymes necessary to 

 convert glucose to pyruvic acid by way of the Embden-Meyerhof 

 pathway. The explanation for its failure to ferment seems to be that 



