Waksman — 152 — Actinomycetes 



On comparing the decomposition of straw by an actinomyces, a fun- 

 gus, a mixed population, and a complex soil infusion (Table 39), it was 

 found that the actinomyces was capable of decomposing a considerable 

 amount of cellulose and lignin. The cellulose-decomposing capacity 

 of the actinomyces was less than that of the fungus Trichoderma. The 

 latter, however, did not attack the lignin, whereas the actinomyces did. 

 The actinomyces synthesized less cell material than the fungus, as shown 

 by the smaller amount of ammonia assimilated. 



Table 39: Decomposifian of wheat straiv by different microorganisms (447): — 



Amount of decomposition in milligrams 



CO2 Ammonia-N 



Organtism liberated Pentosan Cellulose Lignin assimilated 



mg C mg 



Streptomyces sp. - - 215 32 8.2 



Trichoderma sp. 206 201 406 27.3 

 Trichoderma sp.f 



Streptomyces sp.-\ 223 209 434 24 27.1 



Bacterium sp. 



Soil infusion 376 379 572 2 20.5 



t Controls contained 708 mg pentosan, 1,290 mg cellulose, 794 mg lignin and 29-8 mg ammoni.i-nitrogen. 



The decomposition of plant materials by actinomycetes is influenced 

 by a number of factors, such as reaction, aeration, moisture content, and 

 temperature. In a study of the effect of reaction upon the decomposi- 

 tion of dried blood by actinomycetes, as measured by ammonia forma- 

 tion, the maximum activities were found to take place at pH 5.8 to 7.7. 

 Some organisms showed some activity at pH 5.0, but verv little at pH 

 4.0 and pH 8.8. 



Decomposition of Humus:— In view of their capacity to decompose 

 complex plant materials, actinomycetes would be expected to take an 

 active part in the decomposition of organic matter in the soil. This is 

 true of both nitrogenous and nonnitrogenous materials. Because of 



Table 40 : Decomposition of sedge and reed peat by microorganisms (473) : — ■ 

 On the basis of 20 gm of dry peat decomposed for 28 days 



CO2 Ammonia-N Ratio of 



Organism liberated liberated C : N 



mg C mg N 



Streptomyces sp. 87.7 116 76 



Trichoderma sp. 88.4 13-3 6.7 



Soil infusion 68.7 5.8 11.8 



