410 PRINCIPLES OF SOIL MICROBIOLOGY 



in this connection that there is a distinct difference in the usage of 

 the terms "supply, expenditure, utilization and transformation" of 

 energy in the case of autotrophic bacteria on the one hand, and hetero- 

 trophic on the other. In the case of the autotrophic organisms, a 

 part of the energy goes to produce work in the true thermodynamic 

 sense. In the case of the heterotrophic organisms, we can speak of a 

 "supply and exchange of energy" only in specific cases, as in the syn- 

 thesis of fats from carbohydrates, where thermodynamic work takes 

 place. When bacteria or fungi growing in carbohydrate media, store 

 away carbohydrates (hemicelluloses, cellulose or chitin), this is not 

 work in the thermodynamic sense and is carried out with practically 

 no energy transformation. One should differentiate between true 

 syntheses which are also reductions and a mere assimilation of nu- 

 trients. However, the formation of carbohydrates by microorganisms 

 involves only a small loss of energy when carbohydrates are used as a 

 substrate; a greater loss of energy with fats and a very considerable 

 loss of energy when carbohydrates are formed from proteins as a 

 substrate. 49 



Aerobic utilization of energy. Taking glucose as a starting point, 

 the following products of oxidation are produced, depending on the 

 degree of oxidation: 50 



* 9 Terroine, E. F., Bonnet, R., Jacquot, R., and Vincent, G. Rendements 

 £nerg6tiques compares dans le d^veloppement de moissures aux depens d'hy- 

 drates de carbone ou de protdiques et action dynamique sp£cifique. Compt. 

 Rend. Acad. Sci., 177: 900-902, 1923. 178: 869, 1488. 1924. 



60 Kruse, 1910 (p. xii). 



