KLUYVER S CONTRIBUTIONS TO MICROBIOLOGY AND BIOCHEMISTRY 



use of isotopically labeled glucose Gunsalus and co- workers, Gest and 

 Lampen, and Gibbs and De Moss demonstrated that the distribution 

 of the labeled carbon atoms of the substrate among the fermentation 

 products arising under the influence of heterofermentative lactic acid 

 bacteria and /^ymomonas mobilis (Ps. lindneri) is entirely incompatible 

 with the functioning of a mechanism of sugar decomposition whereby 

 the hexose is first broken down to two triose molecules. Present 

 information strongly supports the concept that the reaction sequence 

 consists in an initial oxidation of the substrate to gluconic, and next 

 to keto-gluconic acid; a decarboxylation of the latter; and finally a 

 cleavage of the resulting pentose to a two- and three-carbon fragment. 



Meanwhile De Ley had shown that the potentially fermentative 

 Aerobacter species can also carry out such a direct oxidation of glucose, 

 while Horecker and co-workers discovered a cyclic pathway for the 

 oxidation of glucose via gluconic acid and pentose that now appeals 

 to be of quite general occurrence in many different kinds of cells. 

 Needless to say, these developments have indicated that the old 'uni- 

 tarian theory' can at best be applied to a very much more restricted 

 number of cases than was at first believed. 



In his second Harvard lecture Kluyver discussed in detail some of 

 these newer findings, and introduced the startling change in outlook 

 with the remark: 'Fortunately, however, this age has also its "scep- 

 tical biologists" ' (p. 38), concluding that review with the statement: 

 'Meanwhile we have learned that "there are more paths between 

 heaven and earth" than until recently had been dreamt of in the phi- 

 losophy of the comparative biochemist' (p. 45). 



This sentence represents an admission of the inadequacy of the older 

 concepts. Indubitably it has become evident that the small number of 

 reaction patterns initially envisaged by Kluyver as constituting the 

 whole of biochemistry must be greatly expanded if we are to com- 

 prehend the various biochemical processes in a manner more in keep- 

 ing with mounting experience, and it seems a foregone conclusion that 

 a continued study of biochemical mechanisms will reveal a number 

 of as yet unknown types. 



Kluyver had begun his search for unity in the wild variety of bio- 

 chemical manifestations in 1923. In a single decade this search had 

 produced a theory that has inspired a whole generation and guided 

 its efforts into productive channels. Is it to be wondered at that Kluy- 



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