418 PRINCIPLES OF SOIL MICROBIOLOGY 



coefficient" of storage-rot fungi was found 68 to vary from 3.86 to 

 22.86, while the respiration coefficient varied from 2.9 to 11.4. The 

 respiration of thermophilic fungi is less than that of common fungi. 

 Penicillium sp. produces at 15° in 24 hours enough C0 2 to correspond 

 to 67 per cent of dry weight; at 25°, 133 per cent. By applying the 

 van 't Hoff formula for the temperature coefficient, Noack 69 calculated 

 that, at 45°, 532 per cent C0 2 would be produced by Penicillium, while 

 the thermophilic Thermoascus produced only 310 per cent C0 2 at 45°. 

 The temperature quotient is 1.7-1.9 for 10° temperature difference for 

 Thermoascus and 2-3 for common fungi. 70 



Bacteria utilize for synthetic purposes a smaller amount of the 

 energy made available than do fungi. The utilization is largest with 

 aerobic bacteria. This is further accentuated by the fact that bacteria 

 usually form a larger quantity of intermediary products than fungi. 

 The energy utilization by the various bacteria depends upon the nature 

 of the organism and mechanism of decomposition of substrate, ranging 

 from 37 to 38 per cent of the energy made available in the case of Bac. 

 subtilis and aerobic yeasts to only 0.5 to 7.0 per cent of the energy for 

 urea, acetic, and nitrite bacteria. The lower the relative amount of 

 energy made available the greater is the transformation of matter and 

 energy for the same amount of cell-protoplasm synthesized. The fact 

 that heterotrophic bacteria are capable of synthesizing a large part 

 of the cell constituents by merely assimilating the constituents of the 

 substrate without producing much work, while the urea and autotrophic 

 bacteria have to do work, also explains the lower energy utilization and, 

 therefore, the larger amount of matter and energy transformation in the 

 case of the last group. 



Arnaud and Charrin 71 cultivated Bad. pyocyaneum on a medium 



68 Harter, L. L., and Weimer, J. L. Respiration of sweet potato storage rot 

 fungi when grown on a nutrient solution. Jour. Agr. Res., 21: 211-226. 1921. 



69 Noack, K. Der Betriebstoffwechsel der thermophilen Pilze. Jahrb. wiss. 

 Bot., 59: 413-466. 1920. 



70 Further information on the influence of temperature upon life processes is 

 given by Kanitz, A. Temperature undLebensvorgange. Borntraeger. Berlin. 

 1915; Arrhenius, S. Quantitative laws in physical chemistry, 1915; Crozier, W. 

 J., On biological oxidations as function of temperature. Jour. Gen. Physiol., 

 7: 189-216. 1924. 



71 Arnaud, A., and Charrin, A. Recherches chimiques sur les secretions 

 microbiennes. Compt. Rend. Acad. Sci., 112: 755-758, 1157-1160. 1891. 



