DECOMPOSITION OF NON-NITROGENOUS ORGANIC MATTER 443 



which fall to pieces when an attempt is made to lift them out of the 

 medium. Some actinomyces produce red and black pigments 

 through the paper. However, when compared with the bacteria and 

 fungi capable of decomposing celluloses, the action of most of the 

 actinomyces upon cellulose is only slow and limited. 



Cellulose decomposition by filamentous fungi. The destruction of 

 hemicellulose in plant tissues is to be sharply differentiated from that 

 of cellulose. Fungi act differently upon hemicelluloses of different 

 plants, due probably to the difference in chemical composition of the 

 plant tissues rather than to differences in solubility of the hemicellu- 

 loses. 46 It has been shown elsewhere (p. 263) that fungi possess a 

 strong cellulose-decomposing power, especially certain Fusaria, Asper- 

 gilli, Penicillia, Trichodermae and various Dematiaceae. It has even 

 been suggested that in normal cultivated soils, these organisms play 

 the most important role in this connection. The following method can 

 be used for comparing the cellulose decomposing power of different 

 microorganisms : 



Finely ground filter paper (1 gram) and 20 cc. of a nutrient solution [10 grams 

 (NH 4 ) 2 S0 4 , (NH 4 ) 2 HP0 4 or NH4NO3, 3 grams K 2 HP0 4 , 2 grams MgS0 4 , 1 gram 

 NaCl, 1000 cc. of tap water, with or without 5 grams CaCOs] are added to 100 

 grams portions of sand or soil, placed in flasks, sterilized (for 2 hours at 15 pounds 

 pressure) and inoculated. If possible, it is advisable to connect the flasks with 

 an aeration apparatus and determine the evolution of CO2. When soil is used as 

 a medium, a control without cellulose, sterilized and inoculated should also be 

 employed. When CaCOs is added, allowance should be made for the CO 2 given off 

 by the interaction of organic acids with the carbonate. The cultures are in- 

 cubated for 3 to 6 weeks at 25° to 28°C. At the end of the incubation period, the 

 amount of cellulose left in the 20 grams of the moist culture (allowing for the 

 moisture content) is determined by the quantitative method of Charpentier. 

 A series of results 47 obtained by this procedure, with sand as a medium, are 

 presented in table 36. 



When cellulose is the only source of energy available, one part of 

 nitrogen is assimilated by fungi from inorganic sources added to the 

 medium for every thirty parts of cellulose decomposed. 48 This fact 



46 Schellenberg, 1908 (p. 264). 



47 Waksman, S. A., and Heukelekian, H. Cellulose decomposition by various 

 groups of soil microorganisms. 4th Int. Cong. Pedology. Rome. 3: 216-228. 

 1924. 



48 Heukelekian, O., and Waksman, S. A. Carbon and nitrogen transforma- 

 tions in the decomposition of cellulose by filamentous fungi. Jour. Biol.Chem., 

 66: 323-342. 1925. 



