NATURE OF ANTIBIOTIC SUBSTANCES 



121 



TABLE 20. GROWTH AND PRODUCTION OF STREPTOTHRICIN BY 

 S. LAVENDULAE 



From Waksman (946). 



Note. The organism was grown in i per cent starch medium. 



the active substance is limited unless the organism is grown under sub- 

 merged conditions. Iron appears to play an essential role in the produc- 

 tion of the active substance. An increase in growth as a result of an in- 

 crease in the amino-acid concentration, with the same amount of carbo- 

 hydrate, causes an increase in the production of streptothricin. An in- 

 crease in growth as a result of an increase in carbohydrate concentration 

 does not. 



When the medium contains one amino acid as the only source of car- 

 bon and nitrogen, there is gradual increase in the alkalinity of the 

 medium, resulting in the destruction of the streptothricin. Neither the 

 growth of the organism nor the production of the streptothricin, how- 

 ever, is influenced by the reaction of the medium, within certain limits, 

 even between ^H 4.4 and 8.0 ( 1028). The metabolism of S. lavendulae 

 and the course of production of streptothricin under stationary and sub- 

 merged conditions are illustrated in Figure 1 1 . The bacteriostatic spec- 

 trum of streptothricin is shown in Table 2 1 . It has a certain delayed, 

 even if limited, toxicity to animals and is active in vivo against both 

 gram-positive and gram-negative bacteria (792). 



Different strains of S. lavendulae differ greatly in their ability to pro- 

 duce streptothricin. The possibility that other species of Streftomyces 

 zre also capable of producing streptothricin or closely related com- 

 pounds, as indicated by somewhat different antibiotic spectra, has also 



