KLUYVER S CONTRIBUTIONS TO MICROBIOLOGY AND BIOCHEMISTRY 



nition of the stepwise oxidation processes, supporting the notion of 

 differences in degree of oxidative capacity, along with the discovery of 

 identical modes of sugar fermentation among different groups of bac- 

 teria, these were the starting points for the inception of a theory of 

 metabolism that soon permitted a unified and gratifyingly simple 

 interpretation of metabolic processes in general. 



Following Donker's studies with Aerob. polymyxa, a beginning was 

 made with a coordination of the then existing knowledge of microbial 

 fermentations. Kluyver's outspoken desire to 'discover unity in the 

 wild variety' soon made him perceive that all these processes can be 

 considered as composites of a small number of major reaction types, 

 characteristically displayed by specific groups of microbes. In the first 

 publication on this subject eight groups of organisms were so differen- 

 tiated, and these were shown to comprise only five fermentation pat- 

 terns, as indicated by the products formed. 



Now the possibility to arrange the acetic acid bacteria in order of 

 ascending oxidative capacity was based on the fact that the metabolic 

 end products of one type could be considered as intermediate products 

 of the subsequent types because the latter can further oxidize these 

 compounds. This raised the question whether it might not be possible 

 to use a similar approach in attempting to systematize the extant 

 knowledge of fermentation processes as well. 



An auspicious support for such a possibility was the recognition 

 that in diverse fermentations acetaldehyde had been postulated on 

 good grounds as a more or less constant and crucial intermediate 

 product; in fact, Neuberg had expressed the idea that sugar fermen- 

 tations by various micro-organisms follow very similar paths. A survey 

 of what was known and surmised with respect to different fermenta- 

 tions soon led Kluyver and Donker [1924a] to a synthesis that held 

 out great promise for a unified interpretation. The extent of this syn- 

 thesis can best be appreciated by considering the general pattern that 

 emerged, and that was based on the assumption of not more than four 

 specific reaction types, as follows: 

 /. A primary reaction in which the hexose molecule is split into two 



triose moieties. 



2. Transformation of the latter, either to lactic acid, or to formic acid 

 and acetaldehyde. 



3. Dehydrogenations of formic acid and acetaldehyde. 



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