The Transitionary Stage from Anaerobiosis to Aerobiosis 595 



But the fact that the main path of those various types corresponds to the 

 glycolytic system of Embden-Meyerhof-Pamas (EMP system) without excep- 

 tion indicates that each of them has been generated in close association with 

 each other. This EMP system which is universally distributed in living cells is 

 the fimdamental metabolic system, forming the basis for development not only 

 of the fermentation process but also of photosynthetic and respiratory processes. 

 These observations indicate that though there are certain traits of similarity 

 and a wide array of differences among metabolic systems, a fundamental unity 

 exists in all life processes. 



The primordial form of EMP system that may have been present in the more 

 primitive living units is not found in the present Uving beings as a 'hving fossil', 

 and what type the primordial form may have been cannot now be speculated 

 on and is imknown as far as we know. But when the various types of present 

 fermentation processes are compared with each other, it is to a certain extent 

 possible to speculate which type is original or derived — ^that is, primitive or 

 recent. 



Prof. Oparin considered instability, heterogeneity and low level of energy 

 efficiency in the fermentation type as the reflection of its primitivity, the most 

 primitive living things probably carrying out energy-yielding reaction by the 

 Clostridium type of fermentation. And he concluded that alcohol or lactic acid 

 fermentation is a more highly developed type than this. 



An important process in the Clostridium type of fermentation is the so-called 

 'phosphoroclastic' reaction which occurs in saccharolytic Clostridia [7, 8]. 



CH3 CO COOH + H3P04-^ (C)3 compound -^ CH3 COOPO3H2 + CO2 + Hj 



In lactic acid or alcohol fermentation, electrons which are activated by de- 

 hydrogenation during the EMP process are transferred to pyruvate or acetalde- 

 hyde, that is, the intermediates in this process act as the ultimate acceptor and 

 thus lactic acid or alcohol is produced. But on the other hand, in the clostridial 

 type of fermentation, activated electrons are transferred to the hydrogenase 

 system besides the intermediates as the ultimate acceptor and molecular hydrogen 

 is evolved, being Hberated by acetaldehyde dehydrogenation. 



In homolactic acid fermentation, two molecules of high-energy phosphate 

 are formed by the fermentation of one molecule of glucose, but in the clostridial 

 type of fermentation one or more high-energy phosphates are formed in only 

 the process of pyruvate decomposition. Therefore, the latter fermentation type 

 is higher than the former in point of energy efficiency level. 



The H2-evolving reaction from pyruvate is inhibited by CN and CO radicals 

 which are typical inhibitors of enzymes containing heavy metals as the active 

 centre [9], but the CO inhibition cannot be reversed by light [10]. Furthermore, 

 the author and colleagues [10] have recently demonstrated that the hydrogenase 

 system may contain a metalloflavoprotein, which is not a typical haem protein. 

 In the Clostridium type of fermentation, there is found an enzyme system con- 

 taining heavy metal and more developed than that of homolactic acid fermentation. 

 It is also very interesting that in the presence of metal-complexing agents such 

 as cyanide, CO, the fermentation of glucose results mainly in lactic acid as op- 



