ENERGY SUPPLY OF THE CELL 55 



Part of the acet aldehyde reacts according to Illb and 

 IVa, producing acetic acid and hydrogen, or according 

 to IIIc + IVe, giving ethyl alcohol besides acetic acid. 



The formic acid from Ic is largely split according to 

 Ilia. With some organisms, this hydrogen is liberated 

 as such; others can activate it to reduce either butjn-ic 

 acid, or an intermediary stage of reaction lib, to butyl 

 alcohol; further acetic acid may be coupled according to 

 reaction lie to form acetone. It seems probable that a 

 high hydrogen ion concentration is necessary to perform 

 these latter changes, and this acidity seems to be pro- 

 hibitive for the species forming butyric acid only. 



Other Fermentations shall not be discussed here. It 

 is beyond the scope of this book to describe all different 

 types of fermentations. Such descriptions might be 

 found in the book of Fulmer and Werkman (1929) or in 

 vol. Ill of Buchanan and Fulmer's, ^^ Physiology and 

 Biochemistry of Bacteria." This chapter was meant to 

 give a conception of how a fermentation takes place, 

 and what an equation of fermentation does and does 

 not mean. 



Complete Oxidation of glucose is typical for certain 

 groups of microorganisms, among which the Myco- 

 bacteria are perhaps the most outstanding. No inter- 

 mediary products of any kind could be found by Merrill 

 (1930) in a careful investigation. 



In the oxidation of glucose by molds, intermediate 

 steps are well-known, though the oxidation will finally 

 become complete. Oxidation follows a hydration of 

 the aldehyde group of the glucose molecule: 



CeHi^Oe + H2O = CsHuOs-C— OH = 



CsHnOsCOOH + 2H = Acceptor 



