CHAPTER XVI 



THE UTILIZATION OF CARBOHYDRATES BY BACTERIA 

 ARTHUR ISAAC KENDALL 



Washington University School of Medicine, St. Louis, Mo. 



Man has been familiar with the results of the fermentations induced in saccharine 

 media from the earliest times, but it was not until 1810 that a serious attempt was 

 made to reduce the reactions of a fermentation process to a definite, balanced chemical 

 equation. In that year Gay-Lussac' published his "Memoire sur la fermentation," 

 in which he stated that glucose undergoing alcoholic fermentation passes quantita- 

 tively into carbon dioxide and ethyl alcohol according to the following equation : 



CeHx.Oe = 2 C0.+ 2 C2H5OH . 



Notwithstanding the fact that this equation is an impossible one, as is readily 

 seen from a consideration of the space formula for glucose, the observation is very 

 valuable not only because two of the most important substances produced from the 

 fermentation of glucose by yeast are thus early identified, but also because this is 

 one of the very first attempts to study a biological reaction in a quantitative way. 

 This observation, furthermore, was made at a time when organic chemistry was a very 

 immature science and long before the discovery of the yeast plant itself. 



More than half a century elapsed before the detailed study of micro-organisms 

 and their products of development was resumed. Meanwhile, the compound micro- 

 scope was brought to a state of perfection compatible with accurate observations, and 

 a violent controversy centering on the doctrine of spontaneous generation had brought 

 to light the part microscopic organisms play in inducing fermentations and putrefac- 

 tions in decomposable media. Also new and useful methods for culturing and identi- 

 fying these micro-organisms gradually were developed. The famous controversy be- 

 tween Liebig and Pasteur, which lasted nearly twenty years in the aggregate, termi- 

 nated with the firmly established thesis of "no fermentation without life," which is 

 one of the great contributions of Pasteur to microbiology. About two decades later 

 Buchner discovered zymase, which in turn opened up a new and very fertile field 

 for further exploration. These three great discoveries — first, the chemical balance 

 sheet of fermentation; second, the organism that incites fermentation; and third, 

 the complex enzymatic nature of the process of fermentation itself — although not 

 fully matured even today — mark a new and highly important epoch in the study not 

 only of microbiology, but of cellular activity in general. While it is undoubtedly true 

 that the nature of the decomposition of carbohydrates by yeast is far better under- 

 stood than decompositions induced by bacteria, nevertheless considerable progress 

 has been made along bacteriological lines and much valuable information has been 

 obtained. 



' Gay-Lussac, L. J.: Ann. chim. et phys., 76, 245. 1810. 



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