412 PRINCIPLES OF SOIL MICROBIOLOGY 



In this particular case, tartaric acid and glucose have undergone 

 complete oxidation while for the other three substances it is only partial. 

 For a quantitative determination of respiration of microorganisms the 

 methods suggested by Bieling, 52 Warburg, 53 and Osterhaut 54 can be 

 used. The last is based upon the time required to produce definite 

 changes in the acidity. The hydrogen-ion concentration has no in 

 fluence upon the absolute respiration of fungi or upon the ratio between, 

 growth and respiration, as shown by Gustafson 55 for Pen. chrysogenum and 

 Lundegardh 56 for Fusaria. Phosphate was found to have a favorable 

 effect on respiration. It is of interest to note that phosphate has a 

 specific action in bringing about the auto-oxidation of fructose. 53 



Anaerobic utilization of energy. According to Pasteur, 57 fermentation 

 is the activity of cells in the absence of air or free oxygen, which results 

 in the liberation of energy necessary for the growth and other vital 

 activities of the cells in a manner similar to aerobic respiration in the 

 presence of oxygen. In the absence of air, cells obtain the oxygen 

 from the carbohydrate itself, whereby one half of the carbohydrate 

 molecule is reduced and the other oxidized. In the case of alcoholic 

 fermentation by yeast, alcohol is the reduction product and C0 2 the 

 oxidation product. 



C 6 H 12 6 = 2 CH 3 • CHOH • COOH + 25 Cal. 

 Lactic acid 



C 6 H 12 6 = 2 CH 3 • CH 2 • OH + 2 C0 2 + 27 Cal. 

 Alcohol 



C 6 H 12 6 = CH 3 • CH 2 • CH 2 • COOH + 2 C0 2 + 2 H 2 + 15 Cal. 

 Butyric acid 



62 Beiling, R. Eine Methode zur quantitativen Bestimmung der Atmung von 

 Mikroorganismen und Zellen. Centrbl. Bakt. I, O, 90: 49-52. 1923. 



63 Warburg, O., and Negelein, E. Uber die Reduktion des Salpetersaure in 

 griinen Zellen. Biochem. Ztschr., 110: 66-115. 1920; 142: 317-333. 1923; 

 Warburg, O., and Yabusoe, M. Uber die Oxydation von Fructose in Phosphat- 

 losungen. Biochem. Ztschr., 146: 380-386. 1924. 



64 Osterhaut, W. J. V. Comparative studies on respiration. Jour. Gen. 

 Physiol., 1: 171-179. 1918. 



66 Gustafson, F. G. The effect of hydrogen ion concentration on the respira- 

 tion of Penicillium chrysogenum. Jour. Gen. Physiol., 2: 617-626. 1920. 



66 Lundegardh, H. Der Einflusz der Wasserstoffionenkonzentration in Gegen- 

 wart von Salzen auf das Wachstum von Gibber ella saubinetii. Biochem. Ztschr., 

 146: 564-572. 1924. 



67 Pasteur, L. Etudes sur la biere. Paris. 1876. 



