BIOGRAPHICAL MEMORANDA 



Kluyver, who was a master in the art of 'discovering unity in the 

 wild variety of nature', had meanwhile started the search for a 'quan- 

 titative theory of catalysis' that 'could lead to a sharp characterization 

 of the electrostatic properties of different catalysts', and 'might make 

 it possible to predict the nutritional requirements of the corresponding 

 cells'.* 



It was hoped that a study of the redox potentials established in 

 metabolizing cultures of various micro-organisms would provide a 

 promising approach to this problem, the underlying idea being that 

 the specific affinity of the cells for hydrogen would express itself more 

 or less clearly in the quantitatively measurable potentials. 



In a publication on redox potentials from his laboratory [Elema, 

 Kluyver, and Van Dalfsen, 1934] the nature of the general problem 

 was introduced as follows: 



' . . . a closer study of the connexion between the redox potentials 

 established in microbial cultures and the nature of the metabolic pro- 

 cesses had long been part of the programme of our institute. This was 

 a logical consequence of the attempt to reduce the totality of bio- 

 chemical events to chains of catalytic oxido-reduction reactions. 



'In choosing specific processes for studies of this sort we were 

 guided by the following considerations. Firstly, it was necessary to 

 select a metabolic process that can occur under fully physiological 

 conditions in a medium of very simple composition. Secondly, it 

 seemed essential for the time being to neglect the aerobic metabolic 

 processes because under the usual conditions of cultivation these lead 

 to heterogeneous situations in the culture medium. The slow diffusion 

 of oxygen into the deeper layers of a culture liquid, and the conse- 

 quent uneven distribution of the cells in the cultures will surely result 

 in differences in redox potentials at different distances from the sur- 

 face. 



* The meaning of this latter phrase may easily be misunderstood by the younger 

 microbiologists and biochemists. In 1930, when our knowledge of specific growth 

 factors was as primitive as that of enzymes, Kluyver could not have used the term 

 'nutritional requirements' in its current sense. From the context, and from know- 

 ledge of the evolution of his ideas, it is obvious that he had in mind the possibility 

 of predicting which of the great variety of potentially oxidizable or fermentable 

 substrates - inorganic substances, hydrocarbons, alcohols, polyalcohols, fatty and 

 substituted acids, carbohydrates, aromatic compounds, amines, amino acids, etc. - 

 a particular organism should be able to utilize. 



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