MICROBIOLOGY AND INDUSTRY 



duced a 'mineral yeast' during the war, at which time it acquired im- 

 portance as food for both man and animal. For this purpose a yeast 

 was used that is closely related to the common alcohol yeast but that, 

 when cultivated in shallow layers of liquid exposed to air, displays 

 virtually no fermentative activity so that under these conditions a 

 strictly aerobic respiration is accompanied by a copious multiplication. 

 On Chapman's [1921] authority, who spoke in this connexion of 'true 

 Teutonic enthousiasm', I may state that it was this process that tempted 

 Hayduck to the pronouncement that not until man is in a position to 

 convert his evening newspaper so rapidly into sugar that the protein 

 produced therefrom can be consumed the next morning at breakfast 

 will one of the greatest problems of this century have been solved ! 



It is also worth mentioning that the reverse of the last-mentioned 

 process, viz., a microbiological conversion of the organic nitrogen 

 compounds present in waste materials into inorganic nitrogen com- 

 pounds is the basis of a native British Indian industry that is current- 

 ly still most important in that country. It may surprise many of you 

 to learn that before the war British India, despite a far from negligible 

 native consumption, exported on the average 15,000 tons of salpetre 

 annually, while during the war this figure reached approximately 

 50,000 tons. All of this nitrate had been produced by the natives in a 

 primitive manner, by making use of the powerful bacterial nitrification 

 process that, in the tropics, can proceed under very favourable condi- 

 tions. 



The preceding remarks have opened up many unsuspected prospects 

 for applied microbiology; nevertheless, the existing possibilities have 

 by no means been exhausted. Thus far I have discussed micro-organ- 

 isms as biochemical catalysts more or less on a par with the catalysts 

 of pure chemistry. But this implies a serious undervaluation that calls 

 for a redress. Another aspect is evidently revealed by the power of 

 organisms to reproduce, which consequently means that, in contrast 

 to what happens to purely chemical catalysts, an enhanced production 

 of biocatalysts occurs during microbial conversions as a result of cell 

 multiplication. In addition I must emphasize the great adaptiveness 

 that appears to be inherent in living organisms. In this connexion I 

 think of the surprising modifications in the metabolic properties of a 

 cell under the influence of chemical changes in the medium in which 



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