DECOMPOSITION OF NON-NITROGENOUS ORGANIC MATTER 459 



and not the lignin itself, the latter being very resistant to the action 

 of microorganisms. 98 Very few organisms (largely actinomyces and 

 certain bacteria) are capable of attacking lignins and use them as 

 sources of energy. 



Celluloses and other carbohydrate constituents of straw, such as the 

 pentosans, are completely digested by animals. However, the pres- 

 ence of lignins which thoroughly impregnate the cellulose make the 

 process of digestion more difficult. When the lignins are made soluble 

 or removed by alkaline treatment, the straw becomes a more available 

 source of energy and its digestibility is greatly increased. This re- 

 moval of the lignin can be accomplished by treating the straw with 

 various concentrations of NaOH or Ca(OH) 2 at different temperatures 

 and pressures. In the soil the celluloses and hemicelluloses are de- 

 composed by microorganisms long before the lignins are appreciably 

 acted upon. The very organisms concerned are different. 



Crude plant materials undergo in the soil a series of chemical trans- 

 formations carried out by a number of different organisms; the sugars, 

 starches and proteins are decomposed by some, the celluloses and 

 pentosans by others and the lignins by still others. Conditions 

 favorable and uninjurious to the decomposition of celluloses (such as 

 acidity of medium) may be unfavorable or distinctly injurious to the 

 decomposition of lignins. 



In addition to certain actinomyces and bacteria, higher fungi are 

 capable of decomposing lignins to a limited extent, much less so 

 than celluloses, and it is these organisms which are concerned largely 

 with the rotting of wood. The mycelial filaments penetrate into the 

 woody tissues and cause their decomposition. Most of these fungi be- 

 long to the Basidiomycetes, chiefly Hymenomycetes." Czapek 100 

 suggested that two enzymes (hydromase and cellulase) are active in 

 the reaction. Certain filamentous fungi seem to exert some action 

 upon lignocelluloses, as shown by Otto, 101 who found that Trichothe- 

 cium, Aspergillus and Mucor can dissolve out certain substances from 



98 Fischer, 1923 (p. 693); Waksman, 1926 (p. 447). 



99 Rudan, B. Vergleichende Untersuchungen iiber die Biologie holzerstor- 

 enderPilze. Beitr. Biol. Pflanz., 13: 375. 1917; Hubert, E. E. Jour. Agr. 

 Res., 29: 526. 1924. 



100 Czapek, F. Zur Biologie holzbewohnender Pilze. Ber. deut. bot. Gesell. 

 1899; Ueber die sogenannten Ligninreaktionen des Holzes. Ztschr. physiol. 

 Chem., 27: 141-166. 1899. 



181 Otto, 1916 (p. 265). 



