302 BACTERIOLOGICAL CHEMISTRY 



acid cycle involved in muscle metabolism. Oxalacetic 

 acid can be formed by the condensation of carbon dioxide 

 and pyruvic acid (see p. 258). Oxalacetic acid condenses 

 with a further molecule of pyruvic acid to give cis- 

 aconitic acid which gives rise to citric acid : — 



CO2 + CH3CO.COOH > C00H.CH2.C0.C00H^=^C00H.CH = C(0H)C00H 



(oxalacetic acid) 



— 2H 



COOH.CH = C(OH)COOH + CH3.CO.COOH > COOH.C = CH.COOH 



I + CO2 



CH2.COOH 



COOH.C. = CH.COOH "^^^O COOH.C (OH)— CH2.COOH 



I ' I 



CH2.C00H c: 



(cis-aconitiG acid) (citric acid) 



Neutral Products of Fungi 



Ethyl Alcohol. — Many species of Aspergillus and 

 Penicillium give more or less yields of alcohol, the most 

 effective being A. oryzce which is used in Japan for the 

 production of alcoholic beverages. Many species of 

 Mucor produce alcohol, whilst most Fusarium species 

 give large yields, equivalent to those given by yeasts. 

 Phosphorylation reactions are known to be involved 

 and it is highly probable that the mechanism is very 

 similar to that of ordinary alcoholic fermentation by 

 yeasts. 



Acetaldehyde. — Acetaldehyde has been detected by 

 fixation methods in the case of moulds which produce 

 alcohol. It is very probable that it is an intermediate in 

 other fermentations as well. 



Glycerol. — Glycerol has been found among the products 

 of Mucor, Aspergillus and Penicillium species and seems 

 to be a normal fermentation product. It probably arises 

 by a mechanism similar to that by which it is formed in 

 yeast fermentations. 



