CHARACTERIZATION OF STREPTOMYCES SPECIES 



75 



growth of homologous strains of an organism 



is less inhibited than thai of heterologous 

 forms, added weight could be given to the 

 potential diagnostic value of antibiotic pro- 

 duction. The application of the concept of 

 antibiosis as a major characteristic for the 

 speciation of actinomycetes is not generally 

 accepted, since the metabolism of these or- 

 ganisms is too complicated to give sharp 

 lines of autoinhibition. At most, it can be a 

 varietal rather than a species characteristic. 

 Krassilnikov (1950, 1958, 1960a, 1960b) 

 tended to overemphasize the importance of 

 antibiotics in species characterization of ac- 

 tinomycetes. He made two unjustified as- 

 sumptions: (a) every species synthesizes only 

 one particular antibiotic, (b) antibiotics do 

 not inhibit the growth of organisms belong- 

 ing to the species producing such antibiotics. 

 .Many species and even individual cultures 

 are able to form a variety of different anti- 

 biotics; on the other hand, the same anti- 

 biotic may be produced by different organ- 

 isms. The growth of an organism may in 

 some instances actually be inhibited by its 

 own antibiotic, as with S. fradiae and neo- 

 mycin. Finally, a single culture may produce 

 mutants which either have lost the ability 

 to form a particular antibiotic or have gained 

 the ability to synthesize a totally different 

 antibiotic. It is somewhat dangerous to use 

 assumptions and generalizations as the basis 

 for species characterization. The importance 

 of considering antibiotic formation in the 

 systematization of actinomycetes lias also 

 been emphasized by Gause (1955). 



. 1 ctinophage Sensitivity 



During the last 10 years several attempts 

 have been made to determine whether 

 "phage-typing" of actinomycetes might be 

 of some help in identifying unknown isolates. 

 The results obtained point to several facts 

 which must be kept in mind if one tries to 

 use this procedure for characterizing and 

 classifying Streptomyces species. 



1. Actinophages vary greatly in their host 

 ranges. 



a. Mosl actinophages which were 

 tested against a large number of organisms 

 proved to be polyvalent; that is, they lyse 

 cultures that belong to different species or 

 even genera (different according in our pres- 

 ent species concept, which is based on the 

 system presented here). The data presented 

 by Bradley and Anderson (1958) might serve 

 as an illustration (Table 45, Volume I). The 

 activity of some phages upon members of 

 the genera Streptomyces and \<H-<ir<li<i led 

 these workers to question the validity of 

 separating these two genera, which have ac- 

 tually been placed in two different families 

 within the order Actinomycetales. Activity 

 of a polyvalent Streptomyces phage on two 

 Nocardia species was also found by Gilmour 

 et al. (1959). In a study carried out by St. 

 ('lair and McCoy (1959), however, nine 

 phages which proved to be polyvalent 

 against several Streptomyces species failed to 

 attack any of the four Nocardia species 

 tested. The polyvalent character of other 

 phages tested against other species has been 

 shown also by other investigator.- (Hoehn, 

 1949; Chang, 1953, Rautenstein and Kofa- 

 nova, L957; Cause et al, 1957; Mach, L958; 

 Shirling, 1959a, b; Kutzner and Waksman, 

 1959a; Kutzner, I960). Obviously, therefore, 

 a phage characterized by a wide host range 

 is usually of little value in species differ- 

 entiation, unless one is inclined to be a 

 "lumper" who demonstrates by the use of 

 a polyvalent phage that he is right and the 

 '"splitters" are wrong. 



b. Some phages have been found to be 

 specific, causing the lysis of strains of only 

 a few species or of only certain strains of one 

 species. In the latter case one might be justi- 

 fied in doubting the uniformity of the spe- 

 cies rather than in considering the phage as 

 "superspecific." This seems to be definitely 

 true of the species "*S. griseus," various 



