THE BIOLOGICAL ACTIVITIES OF BACTERIA 55 



specific carbohydrate-splitting* powers of any given species are con- 

 stant and unchanged through many generations of artificial cultiva- 

 tion. Thus, differentiation of the Gram-negative bacteria, the 

 diphtheria group, and to some extent of the members of the pneu- 

 mococcus-streptococcus group, can now largely be made by a study 

 of their sugar' fermentations. 



In most of these cases, as far as we know, the cleavage is produced 

 by a process of hydrolysis. A convenient nomenclature which has 

 been adapted for the designation of these ferments is that which 

 employs the name of the converted carbohydrate adding the suffix 

 "asc" to indicate the enzyme. There are thus ferments known as 

 amylase, cellulase, lactase, etc. 



Amylase (Diastase or Amylolytic Ferment). Amylases or starch- 

 splitting enzymes are formed by many plants (malt) and by animal 

 organs (pancreas, saliva, liver). Among microorganisms amylase 

 is produced by many of the streptothrix group, by the spirilla of 

 Asiatic cholera and of Finkler-Prior, by B. anthracis, and many 

 other bacteria. A large number of the bacteria found in the soil, 

 furthermore, have been shown to produce amylases. By cultivating 

 bacteria upon starch-agar plates, amylase can be readily demon- 

 strated by a clearing of the medium immediately surrounding the 

 colonies. 12 



Since, of course, there are several varieties of starches, it follows 

 that the exact chemical action of amylase differs in individual cases. 

 The determination of the structural disintegration of starch by these 

 ferments is fraught with much difficulty, owing to the polymeric 

 constitution of the starches. Primarily, however, a cleavage takes 

 place into a disaccharid such as maltose (hexobiose), and the non- 

 reducing sugars and dextrin. Beyond this point, however, the 

 further cleavages are subject to much variation and are not entirely 

 clear. The dextrins upon further reduction yield eventually maltose, 

 and this in turn, dextrose. 



Another most interesting example of amylolytic activity is the 

 fermentation of starch by such organisms as the B. Granulobacter 

 Pectinovorum with the production of acetone and butyl alcohol. 

 This reaction is now used industrially for the preparation of acetone, 

 using a corn meal mash as the substrate. Dextrose is first formed, 

 and from this, acetone, butyl alcohol, acetic and butyric acid, to- 



12 Ejkmann, Cent. f. Bakt., xxix, 1901, and xxxv, 1904. 



