VUl 



THE ACTINOMYCETES, VOL. I 



nition that they represent a large and highly 

 important microbial group of universal dis- 

 tribution, possessing numerous biochemical 

 activities, and of great practical potenti- 

 alities. 



From an ecological point of \'ie\v, the 

 interest in the actinomycetes has centered 

 largely upon the study of their occurrence in 

 soils, in composts, in water basins, in the 

 atmosphere, and in the infected tissues of 

 living systems. Their role as causative agents 

 of human, animal, and plant diseases at first 

 attracted wide attention, but more recently 

 this interest became of limited significance. 

 Under some conditions, however, the actino- 

 mycetes may play a highly important role 

 in the causation of certain plant diseases, 

 such as potato scab. 



From a biochemical point of view, interest 

 in the actinomycetes has centered largely 

 upon their role in the transformation of or- 

 ganic matter in the soil and their ability to 

 form antibiotics, vitamins, and enzymes. 

 The interest in the antibiotics produced by 

 actinomycetes has been phenomenal. It all 

 began with the isolation of actinomycin in 

 1940. This was followed by the isolation of 

 streptothricin in 1942 and of streptomycin 

 in 1943, and later of chloramphenicol, the 

 tetracyclines, the erythromycins, the neo- 

 mycins, novobiocin, oleandomycin, nystatin, 

 and numerous others. To date, more than 500 

 different antibiotics have been isolated from 

 cultures of actinomycetes. Many of them 

 have been obtained in the form of pure com- 

 pounds, the chemical nature of which has 

 been determined. Others are still of unknown 

 composition. Nearly 25 of these antibiotics 

 have already found extensive practical appli- 

 cation as chemotherapeutic agents. Of the 

 total 2,400,000 pounds of antibiotics pro- 

 duced in the United States in 1955, valued at 

 more than a half a billion dollars, at least 

 two-thirds have been obtained from cultures 

 of actinomycetes. 



The interest in the antibiotics evoked 



tremendous interest in these organisms, their 

 distribution in nature, their growth and nu- 

 trition under controlled conditions, and 

 finally their biochemical activities. Among 

 the earlier treatises devoted to the subject 

 of actinomycetes, note should be taken of 

 the work of Lieske (1919), Duche (1935), 

 Kriss (1937), Krassilnikov (1938), and Cope 

 (1938). I have personally contributed to 

 many phases of the study of actinomycetes. 

 Following my work on "The cultural prop- 

 erties of actinomycetes," published in 1919, 

 I edited the section on actinomycetes in the 

 \^arious editions of Bergey's Manual, begin- 

 ning with the first in 1923 and including the 

 seventh in 1958. My more recent books in- 

 clude a l)Ook on The Actinomycetes published 

 in 1950 and various volumes and papers on 

 the antibiotics of actinomycetes. 



The rapid accumulation of basic knowl- 

 edge concerning the actinomycetes justifies 

 a comprehensive treatise at this time. In this 

 work, I have made no attempt to review or 

 even to list the extensive literature on this 

 subject. Only certain pertinent references 

 have been selected. In view of the fact that 

 more than GOOO references on the subject of 

 a single antibiotic, streptomycin, had been 

 collected (as of 1952!) one can readily 

 imagine the extensive literature covering the 

 other antibiotics that have found practical 

 application in the treatment of numerous 

 human and animal diseases, in animal feed- 

 ing, and in the preservation of various bio- 

 logical preparations and food materials. And 

 all of tlu^se antibiotic references, of course, 

 would be in addition to the thousands of 

 papers that haxe been published relating to 

 the organisms themseh'cs. 



This treatise is limited to a review of our 

 knowledge of the true actinomycetes. It does 

 not concern itself with the various bacterial 

 forms frequently included among the Actino- 

 mycetales, namely, the mycobacteria, coryne- 

 l)acteria, and mycococci. 



In view of the fre(iuent references to mem- 



