KLUYVER S CONTRIBUTIONS TO MICROBIOLOGY AND BIOCHEMISTRY 



functions. The importance of this attitude is that it made Kluyver 

 recognize, already at this time, the fundamental problem of the man- 

 ner in which the energetic coupling is brought about. The problem 

 was posed in the form of a question ; are the chemists familiar with 

 cases in which two reactions that do not have any components in 

 common can be energetically linked? 



From time to time Kluyver returned to this problem, and, as will 

 be shown later on, he soon found himself in a position where he could 

 make a significant contribution to its solution. 



It also seems desirable to call attention to the fact that the im- 

 portance he attributed in this lecture to the outcome of some exper- 

 iments on the nutrition of A. suboxydans now seems rather misplaced. 

 These experiments had shown that the new bacterium could grow 

 only in media containing, besides an oxidizable substrate, complex 

 nitrogen compounds, such as are found in peptone or yeast extract, 

 with one notable exception : in the presence of mannitol growth was 

 observed in an otherwise mineral medium with an inorganic am- 

 monium salt as the nitrogen source. From these results Kluyver ten- 

 tatively concluded that perhaps the decrease in free energy during the 

 first stages of the oxidation of mannitol and glucose, respectively, 

 might be sufficiently different to enable the bacteria to utilise am- 

 monia nitrogen for the synthesis of protein only during mannitol oxi- 

 dation. We now know that A. suboxydans requires para-amino benzoic- 

 and pantothenic acid for growth, so that it seems reasonable to as- 

 cribe the positive result of the culture in the mannitol-mineral medium 

 to an inadvertent contamination with these substances. But in mineral 

 media supplemented with the two growth factors growth also occurs 

 if, for example, glucose or gluconic acid is supplied as the main carbon 

 source. Hence the arguments about the interrelations between carbon 

 and nitrogen nutrition cannot any longer be taken seriously. 



In spite of this criticism these very arguments are interesting 

 because they show that Kluyver was already beginning to think in 

 terms of what gradually evoked into the concept of 'comparative bio- 

 chemistry'. The parallel drawn between the limited oxidative capa- 

 city of A. suboxydans with its requirement for complex nitrogenous com- 

 pounds on the one hand, and diabetes as a metabolic disease on the 

 other may have been wrong in detail; yet it embodies the principle 

 that, in the late 'thirties, came into prominence when the nature of 



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