THE FORMATION OF SPORES BY BACTERIA 



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RESIDUAL 

 GLUCOSE • 



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r ACETIC ACID 



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TIME IN HOURS 



Figure 4. Pyruvic and acetic acid production vs. time. 



spores in our initial experiment was attributable to the fact that the air 

 supply was not sufficient to satisfy the oxygen demand in this stage 

 of the development of the culture. This difficulty can be overcome in 

 one of two ways: by improving the efficiency of aeration, or by reduc- 

 ing the concentration of the glucose, so that less acid is formed and 

 consequently less oxygen is needed. The latter course also reduces the 

 final spore crop. The metabolic processes going on during vegetative 

 cell growth must, therefore, be quite diflFerent from those that take 

 place in the culture just before sporulation. During the growth of the 

 vegetative cells, the glucose is broken down to acids, but the acids are 

 not utilized. Apparently when the glucose is completely gone, an 

 adaptive enzyme fonns for the utilization of the acids. This accounts 

 for the rise of the pH curve. One may also assume that the oxidation 



