PART 11 

 PHYSIOLOGY OF MICROORGANISMS* 



DIVISION I 

 Nutrition and Metabplism 



Introduction 



General Principles of Nutrition and Metabolism. — The 

 nutrition and metabolism of microorganisms are based on the same 

 principles that regulate animal and plant metabolism; in a general 

 way microorganisms are more closely related to animals than to 

 plants, if viewed from the standpoint of their food, their mode of 

 digestion, and their general physiological nature. Only in a few in- 

 stances, i.e., in the case of life without oxygen (anaerobiosis) and in 

 the ability of some species to use free nitrogen- gas, are there processes 

 unparalleled in the more highly developed organisms. Since it will be 

 necessary frequently to refer to plant and animal nutrition in the 

 course of this discussion, these principles, therefore, are briefly 

 discussed in the following paragraph. 



Green plants feed only on inorganic substances. They assimilate 

 carbon dioxide (CO2) from the air which unites with water, nitrates, 

 potassium, calcium, and other salts of the soil and form the body sub- 

 stances of the plant. The cellulose, starch, sugar, protein and all other 

 compounds constituting the plant cells are produced from these simple 

 inorganic substances. This formation of organic compounds from 

 inorganic compounds requires a certain amount of energy. If a certain 

 quantity of sugar is burned to carbon dioxide (CO2) and to water (H2O), 

 a certain amount of energy is liberated in the form of heat. The heat 

 given off in this case is also a distinct product of combustion. This heat 



♦ Prepared by Otto Rahn. 



