KLUYVER S CONTRIBUTIONS TO MICROBIOLOGY AND BIOCHEMISTRY 



state of continuous and violent agitation. This completely prevented 

 pellicle formation and at the same time assured a plentiful oxygen 

 supply. In such cultures the mould developed in the form of small 

 balls, of uniform size, composed of tangled threads of cells that had 

 originated under conditions as nearly homogeneous as possible. The 

 balls of mycelium could be conveniently handled ; a simple nitration 

 through ordinary filter paper sufficed to collect and wash them free 

 of adhering medium. Thereafter uniform suspensions could be pre- 

 pared from the residue on the filter paper, permitting experiments to 

 be conducted with a rigorous control of factors, varied one at a time. 



Application of this technique to problems of kojic, gluconic, and 

 citric acid formation showed that the results were reproducible to a 

 remarkable degree. This also led to a better specification of the op- 

 timum conditions for the production of these substances, although it 

 contributed little to advancing our understanding of the mechanism 

 whereby they are generated. 



The significance of this new methodology is difficult to overestimate. 

 Foster, in his book 'Chemical Activities of Fungi', has paid due credit 

 to it in the passage: 



'From much of the foregoing it is evident that for the most effective 

 studies on mold physiology and biochemistry, none of the methods 

 already described are completely adequate. Submerged growth cul- 

 tures theoretically and practically afford the closest approach to the 

 ideal method of studying mold metabolism. The principles involved 

 in the technique, and the implications possible for the interpretation 

 of physiological studies with fungi under different conditions were 

 first clearly enunciated in 1933 in a classic paper ... by Professor A.J. 

 Kluyver and his student and collaborator, L. H. C. Perquin. This 

 and subsequent papers by these authors represent the first attempt to 

 study mold metabolism systematically under strictly controlled con- 

 ditions, and to elucidate some fundamental principles obtained 

 thereby' (p. 51). 



Those who are familiar with current practices in the industrial 

 production of penicillin, streptomycin, and other substances formed 

 by filamentous microbes will realize how completely this method has 

 been adopted in microbiological practice. But that this method was 

 devised some twenty five years ago in Kluyver's laboratory, and 

 on purely theoretical grounds, is insufficiently appreciated. 



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