Chapter VIU 



DISTRIBUTION OF ACTINOMYCETES 

 IN NATURE 



Actinomycetes are among the most widely distributed groups of 

 microorganisms in nature. Very few natural substrates are entirely 

 free from them. In some of the substrates, as in soils, in lake water and 

 in lake bottoms, in composts, they lead a normal existence. In other 

 substrates, as in sea water and in dust, they are only in a transitory state. 



The ability of actinomycetes to survive for a long time is indicated 

 by the fact that Omelianski isolated an actinomyces (A. elephantis 

 frimigenW) from the slime of a mammoth's nose. This culture showed 

 no particujar properties which would distinguish it from the common 

 actinomycetes found in soils. It must be added, however, that the slime 

 removed from the mammoth, upon its discovery, was kept, without spe- 

 cial precautions of preservation, for several months previous to the iso- 

 lation of the organism (323). 



Actinomycetes are found abundantly in all soils throughout the 

 world; they make up, in many cases, especially under dry alkaline con- 

 ditions, a large part of the microbial population of the soil. They also 

 occur on plant residues and upon and in various foodstuffs, such as 

 fruits, vegetables, milk and milk products, and cacao. The open sea 

 is the only important natural habitat where they, like most of the true 

 fungi, are almost entirely absent; whenever their presence has been re- 

 ported, it was limited to waters close to shore or to waters subjected to 

 land wash, or it was limited to growth upon submerged surfaces, notably 

 piers and other landmarks. Actinomycetes are found in peat bogs, usu- 

 ally in the surface layers where oxygen is present, although occasionally 

 they are also found at greater depths. 



Comparatively few types of actinomycetes are known to be capable 

 of causing plant and animal diseases, but both aerobic and anaerobic 

 actinomycetes may be concerned with human and animal infections. 

 Some of these are deep-seated and involve special methods of treat- 

 ment. 



Our knowledge of the occurrence of actinomycetes in nature dates 

 back to the early days of bacteriology. Following the early observations 

 and descriptions of various actinomycetes by F. Cohn and by Bollinger 

 and Harz, Miquel (301), in 1879, in connection with his work on the 

 bacteria of dust over Paris, carefully described certain actinomvcetes. 

 The full significance of the nature and importance of these organisms 



