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The Enzymes of B. coli communis. Part Y. — (a) Anaerobic 

 Growth folloiced hy Anaerobic and Aerobic Fermentation. 

 (b) The Effects of Aeration during the Fermentation. 



By E. C. Geey and E. G. Young. 



(Communicated by Prof. F. G. Hopkins, F.R.S. — Eeceived February 1, 1921.) 



In the present communications the effect of oxygen upon the fermentation 

 of glucose and upon the growth of the bacteria, in so far as this affects 

 fermentation, is considered. To this end the organisms have been grown both 

 aerobically and anaerobically, and subsequently made to ferment glucose, both 

 aerobically and anaerobically, with the object of comparing the products of 

 decomposition in the two cases. There are clearly two problems : firstly, the 

 effect of exposure to oxygen during growth upon the subsequent fermenta- 

 tion, whether aerobic or anaerobic, and, secondly, the effect of oxygen 

 admitted during the fermentation. The first question relates to the part 

 played by oxygen in the formation of enzymes, the second to the part played 

 by oxygen in their action on carbohydrates. The first question is considered, 

 though in but a preliminary way, in Section A, the second, more fully, in 

 Section B. 



Section A. 



Object of the Experiments. 



Two results were aimed at in these experiments. Firstly, to compare the 

 products of fermentation of glucose anaerobically, after anaerobic growth, 

 with the products of fermentation anaerobically after previous growth 

 aerobically. And, secondly, to obtain information as to the effect of intro- 

 ducing oxygen during the fermentation itself. This latter consideration, 

 however, though brought to notice by these experiments, is considered only 

 incidentally here because it forms the subject of Section B. In the present 

 section we wish to direct attention particularly to those differences which 

 exist between the fermentation after anaerobic and aerobic growth, not upon 

 the effect of aeration during the fermentation. To point out the difference 

 which previous growth aerobically or anaerobically has made, several analyses 

 from previous experiments are included in Table IV side by side with the 

 completely anaerobic experiments of Tables I, II, and III. 



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