24 PRODUCTS OF BACTERIAL ENERGY 



From the bodies of ground yeast cells a soluble ferment, 

 Zymase, has been expressed, which causes alcoholic fermentation 

 of cane and grape sugars. This fact proves that fermentation 

 is not necessarily a vital process. The fermentations of bacterial 

 enzymes may give acids, and also aldehydes, ketones, CC>2, 

 CO, H, N, NH 3 , marsh gas and H 2 S. The carbohydrate splitting 

 powers are used in determinative bacteriology. 



Fermentation and putrefaction are bacterial enzymic processes 

 of indispensible importance to life. Bacteria reduce excrementi- 

 tious matters to their elements and then others build up these 

 elements into conditions favorable for plants. This process 

 affects the cycle of utility of carbon, sulphur and particularly 

 nitrogen in the air and soil. Some soil bacteria can fix nitrogen 

 from the air for the use of plants. Because of the importance of 

 these processes, culture of appropriate bacteria may be spread 

 upon exhausted soil. These are chiefly nitrifying bacteria. 

 Manure contains the denitrifying organisms. Bacterial fermenta- 

 tions produce the flavor of tobacco, opium and butter. 



Enzyme Production by Bacteria. These products are difficult 

 to define because few have been obtained in an entirely pure 

 state. They may be described as soluble, but non-dialyzable 

 products, precipitable by salts of heavy metals or by alcohol, 

 destroyed by 70 but resisting drying and decomposition. 

 They are restrained by excess of alkali, of acid, and by an accum- 

 mulation of their own products. Ferments of great variety 

 and power are formed by the zymogens, as proteolytic, which dis- 

 solve proteids, such as casein; tryptic, gelatine liquefying; diastase, 

 which converts starch into sugar; invertase, which changes cane 

 sugar into grape sugar; ferments that curde the casein of milk; 

 and it may well be that the activity of pathogenic bacteria in the 

 body is due to ferments of some kind. The hemolytic action of 

 the golden staphylococcus or the tetanus bacillus is thought, by 

 some, to be of enzymic nature. 



Organized ferments (bacteria, yeasts) differ from the unorganized 



