DKSCRII'TIOX OF Sl'KCIKS OF STREPTOMYCES 



275 



Sucrose: Inversion. 



Nitrate reduction: Positive. 



Tyrosinase reaction: Strong. 



Antagonistic properties: Certain strains 

 show positive antimicrobial action; others 

 are negative. 



Habitat: Numerous strains of this organ- 

 ism have been isolated from various forms of 

 potato seal) and sugar beet seal) throughout 

 the world. True causative agent of seal). 



Remarks: According to Hoffmann (1058), 

 growth on synthetic agar is reddish with 

 dark gray aerial mycelium; on glucose agar, 

 growth is colorless with blue-gray aerial my- 

 celium; on asparagine agar, growth is dark 

 red with no aerial mycelium. 



Closely related forms include S. clavifer, 

 S. spiralis, S. carnosus, and S. sampsonii 

 described by Millard and Burr; also .1. 

 xanthostromus and .1. ochroleucus of Wollen- 

 weber. Various strains differ in the amount 

 of aerial mycelium produced and in their 

 biochemical properties. 



Type culture: [MRU 3018. 



224. Streptomyces setonii (Millard and 

 Burr, 1926) Waksman (Millard, W. A. and 

 Burr, S. Ann. Appl. Biol. 13: 580, 1926). 



Morphology: Sporophores straight, wavy, 

 formed in clumps. Spores oval, 0.6 to 0.8 by 

 0.85 a. 



Sucrose uitrate agar: Growth abundant, 

 smooth, yellow to brown. Aerial mycelium 

 gray to olive-buff. Soluble pigment faint 

 yellowish to brown. 



Nutrient agar: Growth colorless. Aerial 

 mycelium smooth, white. Soluble pigment 

 brownish. Melanin-negative. 



Glucose agar: Growth lichenoid, gray to 

 brown. Aerial mycelium abundant, white to 

 olive-buff. Soluble pigment golden brown. 



Potato: Growth heavy, wrinkled, brown 

 to red-violet. Aerial mycelium abundant, 

 white to green to olive-buff. 



Gelatin: Surface growth gray. Aerial my- 

 celium white. Rapid liquefaction. Soluble 

 pigment brownish. 



Milk: Surface growth, covered with ring 

 of white aerial mycelium. Questionable co- 

 agulation, followed by rapid peptonization. 



Starch agar: Growth cream-colored. 

 Aerial mycelium patchy, white. Hydrolysis. 



( lellulose: ( rrowth colorless. 



Nitrate reduction: Positive. 



Temperature: Grows well at 37.5 C. 



Habitat : Scabby potatoes. 



Remarks: Millard and Burr also described 

 a similar form under the name .1. setonii 

 flavus. Ettlinger et al. (1058) consider this 

 organism as a strain of S. griseus. Hoffmann 

 (1058) described an organism with lighl gray 

 aerial mycelium as a strain of S. setonii. 



Type culture: [MRU 3375. 



225. Streptomyces somaliensis (Brumpt, 

 10011; emend. Erikson, 1935) Waksman 

 (Brumpt, E. Arch. Parasitol. Paris 10: 480, 

 100(1; Precis de Parasitologic. Paris, 2nd ed., 

 p. 0(17, 1913; Erikson, D. Med. Research 

 Council (Brit.) Spec. Rept. Ser. Xo. 203: 

 1035, p. 17-18). 



Morphology: Substrate growth made up of 

 simple branching, unicellular mycelium with 

 long straight filaments. Aerial mycelium 

 forms straight nonsegmented sporophores 

 with typical chains of spores, 1.25 yu in 

 diameter. 



Glucose-asparagine agar: Growth thin, 

 smooth, and soft. 



Glycerol nitrate agar: Growth abundant, 

 colorless to dark gray and black. 



Nutrient agar: Growth abundant, granu- 

 lar, yellowish, with small discrete colonies al 

 margin; later growth colorless, colonies 

 umbilicated. 



Potato: Colonies round and oval, partly 

 piled up in rosettes. Aerial mycelium whitish- 

 gray. Plug discolored. Pater, aerial myce- 

 lium becomes transient, growth nearly black. 



Blood agar: ( Irowth in form of small, dark 

 brown colonies. Pound and umbilicated, 

 piled up in confluent bands. Reverse red- 

 black. Blood hemolyzed. 



Dorset's ege medium: (Irowth colorless. 



