Chapter VII — 125 — Antagonistic Properties 



upon the streptomycin-sensitive strains. The conclusion was reached, 

 therefore, that the streptomycin-producing cukures isolated in 1943 were 

 identical with the 1915 isolate, that the latter has undergone con- 

 siderable change in culture when grown for 30 years upon synthetic 

 media, and that the 1915 isolate probably possessed the capacity for 

 producing streptomycin, but has lost such capacity upon continuous 

 growth upon artificial media (465a). 



CULTURE BRQTH 



I 



ADSORPTION ON CHARCOAL 



I 



ELUTION BY CH.OH-HCOoH 



I 



PRECIPITATION-PICRIC ACID 



I 



CONVERSION TO HYDROCHLORIDE 



CHROMATOGRAPHY ON ALO. OR CHARCOAL 



PRECIPITATION BY METHYL ORANGE 



CRYSTALLINE HELIANTHATE 



STREPTOMYCIN HYDROCHLORIDE- 



C01H3T.30N7O10.3HCI 



Fig. 26.— Method of isolation of streptomycin from metabolite solution. 



Many other strains of S. griseiis have now been isolated (65, 475) 

 from soils, waters, river muds, animal excreta, dust, and other natural 

 substrates. Only very few of these have been found capable of produc- 

 ing streptomycin, the majority being inactive or producing another anti- 

 biotic, such as grisein (357). Ability to form streptomycin may, there- 

 fore, be considered as a strain rather than as a species characteristic, in 



