206 



THE ACTINOMYCETES, Vol. I 



verted xanthomycin A to the crystalline 

 hydrochloride, the elemental analyses giving 

 CaiHgeNA-SHCl. The anlil)i()tics showed 

 characteristic quinoid properties and con- 

 tained four methoxyl groups and one methjd- 

 imide group. Prolonged reaction shows the 

 release of two primary amino groups. They 

 were soluble in organic solvents. Acid hy- 

 drolysis gave ethanolamine, methylamine, 

 and ammonia in a ratio of 2: 1 : 1 . Separation 

 of A and B was accomplished by Craig 

 countercurrent distribution. Xanthomycin 

 strongly inhibits the growth of many gram- 

 positive and gram-negati\'e bacteria, but 

 does not affect M. tuberculosis in dilutions 

 as low as 1:2000. It is very toxic to experi- 

 mental animals. 



It is important to add further that, in the 

 presence of certain metallic ions, some anti- 

 biotics may form pigmented compounds. 

 The tetracyclines give green compounds 

 with copper and nickel and red compounds 

 with ferrous and ferric iron (Albert). 



Luminescence of Actinomycetes 



Certain actinomycetes have frequently 

 been observed to give off luminescence under 

 given conditions of culture. According to 

 Rudaya (1958), there exists a correlation be- 

 tween the antibiotic activity of S. rimosus 

 and its luminescence intensity in the ultra- 

 violet. This is true especially when the cul- 

 tures are grown on solid media. The rate of 

 luminescence depends on the composition of 

 the medium and on the age of the culture. 

 The character of the luminescence was found 

 to change with cultivation and storage, yel- 

 low luminescence being replaced by a blue 

 one. Certain variants show only bright yel- 

 low luminescence. It has been suggested that 

 luminescence analysis be used as a guide for 

 the primary selection of S. rimosus strains 

 by subjecting young cultures to ultraviolet 

 irradiation on solid media which are favor- 

 able for antibiotic production. 



