SOIL ACTINOMYCES 299 



trations (0.01 per cent), are also utilized. Creatinine is readily utilized; 

 urea and acetamide are assimilated only to a limited extent by the 

 majority of organisms, while a few forms may utilize the substances 

 readily. 35 Lieske found that urea forms an excellent source of nitrogen, 

 while asparagine was only scantily utilized ; uric and hippuric acids were 

 not assimilated. 



The proteins are decomposed, with the formation of ammonia, even in 

 the presence of available carbohydrates, such as glucose. In other 

 words, we do not observe here that sharp sparing action of the carbo- 

 hydrate upon the decomposition of proteins, as in the case of fungi or 

 bacteria. Guittonneau 36 demonstrated that certain actinomyces are 

 capable of producing urea from proteins, both in the presence and ab- 

 sence of glucose, in addition to ammonia. 



Oxygen requirement. The influence of oxygen tension on actinomyces 

 is still an undecided question. There is no doubt that the majority of 

 soil actinomyces are aerobic. The fact that some are able to grow deep 

 into the medium would indicate ability to grow under semi-anaerobic 

 conditions. Beijerinck 37 classified the actinomyces as facultative anae- 

 robes. Lieske, among others, found that the actinomyces acting as 

 animal pathogenes are anaerobic, while the saprophytic forms are 

 chiefly aerobic. A. scabies will not germinate in the absence of oxygen; 

 the amount of available oxygen is the limiting factor both for germi- 

 nation and growth. 373 Other investigators 38 pointed out that the 

 recognition of strict aerobes or anaerobes is based upon errors of tech- 

 nic, since in no instance could a strict aerobe or anaerobe be obtained. 



Influence of temperature, drying and radiation. Some actinomyces 

 grow slowly at temperatures of 3° to 6°. Good growth of most species is 

 obtained at 6° to 38°, 13° to 32°C. being the optimum for the majority 

 of soil forms. Few organisms can thrive at 40-42° and none will grow 

 at temperatures above 46°C. except the thermophilic forms. The 

 temperature limits may be raised a few degrees by gradual adaptation. 



86 Waksman, S. A. Studies in the metabolism of actinomycetes. III. Nitro- 

 gen metabolism. Jour. Bact., 5: 1-30. 1920. 



88 Guittonneau, G. Sur la production de l'uree au cours de rammonifica- 

 tion par les Microsiphondes. Compt. Rend. Acad. Sci., 178: 1383-1385. 1924. 



37 Beijerinck, M. W. Uber Chinonbildung durch Streptothrix chromogena 

 und Lebensweise dieses Mikroben. Centrbl. Bakt. II, 6: 2-12. 1900. 



37a Sanford, G. B. Some factors affecting the pathogenicity of Actinomyces 

 scabies. Phytopath., 16: 525-548. 1926. 



83 Musgrave, W. E., Clegg, M. T., and Polk, M. Streptothricosis with special 

 reference to the etiology and classification of Mycetoma. Philip. Jour. Sci., B., 

 Med. Sci., 3: 447-544. 1908. 



