Streptomyces griseus (Krainsky) Waksman and Henrici 



S. griseus, as a typical Streptomyces, produces both a vegetative and 

 an aerial mycelium. The former varies in thickness from 0.3 to 2\l 

 (0.5-1.3[x). It is (64) well developed, coenocytic when young, and 

 branched in a typical monopodial form; occasionally two or more 

 branches grow from the same place on the main hyphae; no true septa 

 have been observed in the young vegetative mycelium, but are found in 

 the older mycelium, and especially in the sporulating hyphae. The 

 aerial mycelium is at first whitish, but later changes upon sporulation to 

 yellowish green, with varying shades of cream, gray, buff, and browoiish, 

 depending on strain of organism and culture medium. The sporogen- 

 ous hyphae may be borne directly upon the vegetative mycelium, sev- 

 eral filaments arising from the same vegetative hyphae. Good sporulat- 

 ing strains produce straight, well branched sporogenous hyphae. 



The spores are produced exogenously in chains on the aerial 

 mycelium, over 200 spores having been counted (64) in a single chain 

 of 3-day old cultures. The aerial sporogenous h)rphae are often clavate 

 and are continuous; transverse septae are laid down simultaneously, di- 

 viding the h^^pha into mononucleate or multinucleate segments. The 

 cells between the septae increase in size, constrictions appearing at the 

 septae, the spores being held in chains and in connection with each 

 other by narrow fragile bridges. The spores vary in shape from spheri- 

 cal to cylindrical and in size from 0.7 to 0.9 X 0.7-1.9[jl, the variations 

 being observed in the same chain, as shown in Fig. 13. 



The spores germinate at one or both ends, usually at the previous 

 points of attachment to other spores. The germ tubes elongate by 

 apical growth, the spore contents passing into it. The resulting myce- 

 lium branches and later leads to the formation of reproductive mycelium. 

 A nucleus has been demonstrated in the spores, germ tubes, and young 

 mycelium (64). The nuclei move with the cytoplasm. The spores 

 are mononucleate or multinucleate. 



The cultural characteristics of this organism have been (34) briefly 

 described as follows: 



Gelatin stab: Greenish-yellow or cream-colored surface growth with brownish 

 tinge. Rapid liquefaction. 



Synthetic agar: Thin, colorless, spreading, becoming olive-buff. Aerial myce- 

 lium thick, powdery, water-green. 



Starch agar: Thin, spreading, transparent. 



Dextrose agar: Elevated in center, radiate, cream-colored to orange, erose 

 margin. 



Plain agar: Abundant, cream-colored, almost transparent. 



Dextrose broth : Abundant, yellowish pellicle with greenish tinge, much folded. 



