Waksman — 38 — Actinomycetes 



typical aerial mycelium; this mutant forms no streptomycin but another 

 antibiotic which is not active against gram-negative bacteria. 



The life cycle of S. griseiis in relation to the production of strepto- 

 mycin has been described (481) as follows: 



The growth of S. griseus reaches a maximum in stationary cultures 

 in 10 days and in submerged cultures in 3 to 5 days, followed by the 

 lysis of the mycelium. Growth is accompanied by a gradual rise in 

 the pH value of the culture, and in the ammonia and amino nitrogen 

 contents. The total nitrogen in the mvcelium tends to be higher during 

 the active stages of growth. The production and accumulation of strep- 

 tomvcin parallels the growth of the organism. After maximum activity 

 has been reached, there is a drop in activity, which is rapid in sub- 

 merged cultures. For the production of streptomycin, the presence in 

 the medium of an organic substance is required. This substance may 

 either serve as the precursor of the streptomvcin molecule as a whole or 

 of an important group in the molecule, or it may function as a prosthetic 

 group in the mechanism essential for the svnthesis of the streptomycin. 

 Such a factor can graduallv be synthesized by the organism, when it is 

 provided in the medium in a preformed state, however, as in meat ex- 

 tract or in corn steep liquor, the process of streptomycin synthesis is 

 greatly facilitated. Streptomycin is also formed in purely synthetic 

 media. 



In addition to the streptomycin complex, S. griseus produces at least 

 2 other antibiotics one of which, actidione, is active only against fungi, 

 and another, streptocin, which is present in a limited amount in the 

 culture filtrate but more abundantly in the mycelium. Streptocin is 

 soluble in organic solvents and is not active against gram-negative bac- 

 teria. 



Streptomyces lavendulae (Waksman and Curtis) Waksman and Henrici 



S. lavendulae also represents a large heterogeneous group of organ- 

 isms which differ greatly in some of their biochemical properties, notably 

 the production of antibiotic substances. 



The first culture of S. lavendulae was isolated from a New Jersey 

 soil in 1915 (460). Its early description was given (34) as follows: 



Mycelium and hyphae coarse, branching. Spirals close, 5 to 8/Lt in diameter. 

 Conidia oval, 1.0 to 1.2 by 1.6 to 2.0/li. 



Gelatin stab: Creamy to brownish surface growth. Liquefied. 



Synthetic agar: Thin, spreading, colorless. Aerial mycelium cottony, white, 

 becoming vinous-lavender. 



Starch agar: Restricted, glistening, transparent. 



Plain agar: Gray, wrinkled. 



Dextrose broth: Abundant, flaky sediment. 



