Waksman 



150 



Actinomycetes 



A more detailed study of the utilization of glycine by different micro- 

 organisms (p. 81) brought out some very interesting facts. In the 

 presence of glucose, the amount of growth made by the fungus Triclio- 

 derma was much greater than that made by the Streftomyces. The 

 amount of growth produced was somewhat parallel to the amount of 

 glucose decomposed. The actinomyces, however, liberated a greater 

 proportion of the nitrogen in the glycine as ammonia even in the pres- 

 ence of glucose, actually about 50 per cent of the nitrogen of the amino 

 acid decomposed being thus liberated. In the presence of glucose, the 

 fungus apparently utilized most of the nitrogen for cell synthesis. 



Various species of actinomycetes have been found (485) capable 

 of attacking rather readily native proteins of both plant and animal 

 origin, such as zein, edestin, gliadin, albumin, and casein. The ratio 

 of the protein decomposed to cell substance synthesized was 9:1 for the 

 actinomycetes, as compared to 22:1 for bacteria and 5.6:1 for fungi. 



Table 38 : Decomposition of xylan by actinomycetes (462) : — 



The corresponding ratios of nitrogen in protein to nitrogen in cell ma- 

 terial were 20: 1, 24: 1, and 17.6: 1. The actinomvcetes were thus found 

 to occupy an intermediate position between the bacteria and the fungi 

 as regards the ratio of protein decomposition and cell synthesis. 



Actinomycetes are able to utilize a great variety of carbohydrates, 

 including not only simple sugars and starches, but also hemicelluloses 

 and cellulose. Their action upon the more complex compounds is fre- 

 quently selective in nature, being limited to certain organisms. In the 

 decomposition of hemicelluloses, for example, actinomycetes were found 

 (462) to be more effective than fungi. This process was influenced by 

 the nature of the carbohydrate and by the environmental conditions. 

 The process of decomposition can be measured conveniently by the 

 amount of COo liberated. In order to decompose the hemicelluloses, 

 the organism requires available nitrogen for cell synthesis, a definite 

 relation existing between the two, as shown in Table 38. Some species 

 of actinomycetes are capable of decomposing cellulose very rapidly. 

 Under conditions favoring their development, as in neutral alkaline and 

 arid soils or with insufficient moisture, actinomyces may play an impor- 

 tant part in this process. 



