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THE ACTINOMYCETES, Vol. II 



otics. They emphasized that although first 

 listed by Krainsky in 1 ( .)14, S. griseus was 

 amended and described in detail by Waks- 

 man in L919. They further added: 



"If we examine the characteristics given 

 by Krainsky we are led to link this species 

 with A. viridis. This conclusion appears still 

 more logical when we study the coloured 

 taldes prepared by Krainsky. However, in 

 view of the impossibility of comparing 

 Krainsky's original strain and the difficulties 

 that would arise if one did not accept Waks- 

 man's amendment for a species so generally 

 studied in laboratories, it appears advisable 

 to take as definite the characteristics speci- 

 fied by the American author and given in 

 Bergey's Manual .... Numerous strains have 

 been isolated by us and compared, with 

 satisfactory results, with Waksman's strains. 

 . . .There is a considerable body of literature 

 dealing with this species which has a faculty 

 for mutation." 



Baldacci and Comaschi later (1956) wrote: 



"The examination of Krainsky 's descrip- 

 tion and colored pictures would suggest that 

 this species belongs to .1. viridis Lombardo 

 Pellegrino (1903). The comparison between 

 Krainsky's and Waksman's descriptions 

 gives evidence — as even Waksman has par- 

 tially pointed out — to the difference of 

 proteolytic activity and. according to our 

 opinion, the very important difference of the 

 color of the sporulating colonies which are 

 greenish in Krainsky's description. If we ac- 

 cept Waksman's correction of the species 

 and compare his descriptions with our 

 strains, we find a perfect identity. Since it is 

 impossible to compare the original strain of 

 Krainsky with the others, the acceptance of 

 the correction proposed by Waksman offers 

 the advantage of maintaining the name 

 "griseus" for an actinomycete so largely 

 spread oul and studied in laboratories, so 

 thai we agree with it according to this mean- 

 ing." 



Many other cultures of S. griseus have 



since been isolated from soils, river muds, 

 animal excreta, water, dust, and other nat- 

 ural substrates, No1 all of them were found 

 capable, however, of producing streptomy- 

 cin; the majority of these cultures were 

 either inactive or produced other antibiot ics, 

 such as cycloheximide, grisein, streptocin, 

 actinomycin, and candicidin. Some of the 

 cultures yielded a mixture of streptomycin 

 with other antibiotics. The ability to form 

 streptomycin was at first considered as a 

 strain, rather than a species, characteristic; 

 later, however, it was decided (Waksman, 

 1959) to raise S. griseus to the status of a 

 series and the streptomycin-producing 

 strains to a species status, Streptomyces 

 griseus, Waksman and Henrici. 



Several procedures were developed for the 

 isolation from natural substrates and for the 

 identification of streptomycin-producing 

 strains of S. griseus. These methods were 

 based on certain physiological properties of 

 the organisms and on the nature and ac- 

 tivities of the streptomycin formed by them: 



1. Tolerance to fairly high concentrations 

 of streptomycin in the medium. When a 

 soil or other natural material was plated 

 out on a medium containing 50 mg of strep- 

 tomycin per liter, the great majority of bac- 

 teria and actinomycetes failed to develop on 

 the plate. Most of the actinomycete colonies 

 were found to be of the S. griseus type. 



2. Ability of certain resistant strains of 

 test bacteria to grow in the presence of 

 streptomycin. 



:;. Sensitivity to a specific actinophage. 

 When cultures of S. griseus are tested for 

 their sensitivity to a specific actinophage 

 which is active only upon the streptomycin- 

 producing species, the inactive forms or those 

 producing other antibiotics can be easily 

 eliminated. 



4. Utilization of streptomycin-dependent 

 strains of bacteria in testing for strep- 

 tomycin. When a culture of S. griseus or of 

 another organism suspected of producing 



