192 CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 



TABLE 23- GROWTH OF STREPTOMYCES LAVENDULAE AND PRODUCTION 

 OF STREPTOTHRICIN ON TRYPTONE-STARCH MEDIUM 



From Waksman (946). 



acid, a precipitate is produced, the filtrate containing virtually all the 

 activity. 



Streptothricin is completely adsorbed, at neutrality, on charcoal, 

 from which it can be removed by treatment for 8 to 1 2 hours with dilute 

 mineral acid or acid alcohol. The acid extract is neutralized and con- 

 centrated in vacuo y at 50° C, just to dryness j the residue is extracted 

 with absolute alcohol, filtered, evaporated, and taken up in water. It 

 can also be precipitated from the neutralized solution with ether or 

 acetone. Further concentration and reduction in ash content can be ob- 

 tained by subsequent treatments. On electrodialysis, the active sub- 

 stance moves to the cathode at fH. 7.0. 



Streptothricin has been crystallized as the Reinecke salt (300). The 

 crystals consist of a cluster of fine platelets which decompose at 192° 

 to 194° C. after sintering at 184° C. The molecule was found to corre- 

 spond to the di-reineckate of a base C13H25O7N5 j the a-amino nitrogen 

 was 20 to 22 per cent of the total nitrogen. The molecule of streptothri- 

 cin is thus believed to contain at least five nitrogen atoms, two of which 

 are present as salt-forming basic groups j it is free of O-methyl, N- 

 methyl, and hydrolyzable acetyl groups. Streptothricin is stable be- 

 tween fH I and 8.5, but is destroyed by high alkalinity. The activity of 



