Streptomyces poolensis and Streptoinyces tiunuli belong to this group. Source: Isolated from a small, unruptured potato scab. Habitat: Found in potatoes so far as known. 123. Streptomyces praecox (Millard and Burr, 1926) Waksman, 1953. (Actino- myces praecox Millard and Burr, Ann. App. Biol., 13, 1926, 601; Waksman, in Waksman and Lechevalier, Actinomj-cetes and Their Antibiotics, Baltimore, 1953, 107.) prae'cox. L. adj. praecox premature, pre- cocious. Vegetative growth: Raised, colorless. Aerial mycelium: Well developed, gray with greenish tinge. Sporophores produce open spirals. Spores spherical or ellipsoidal, 0.8 micron in diameter. Gelatin: Good growth. Abundant, white aerial mycelium. Liquefaction. Agar: Thin, colorless growth. Aerial mycelium thin, white. Sjmthetic agar: Thin, powdery growth. Aerial mycelium white to olive-buff. Synthetic glucose agar: Flat growth with radiating margins. Aerial mycelium white to olive-colored. On cultivation, aerial mycelium is only white. Starch agar: Thin, cream-colored growth. Aerial mycelium abundant, white with greenish tinge. Broth: Cream-colored surface pellicle. Aerial mycelium thin, white. No soluble pigment. Glycerol synthetic solution: Heavy sur- face growth. Aerial mycelium abundant, powder}', white. Pale yellow soluble pig- ment. Glucose broth: Flocculated growth at bottom and heavy, wrinkled growth at sur- face. Aerial mycelium abundant, white. Milk: Cream-colored surface growth in form of a ring. Aerial mycelium white. Ac- tively coagulated; rapidly peptonized. Potato: Good, cream-colored to light brown growth. Aerial mycelium white to olive-buff. Plug olive-buff to drab. On culti- vation, no soluble pigment produced. Starch is hydrolyzed. Tyrosinase reaction: Negative. Nitrate reduction variable. Odor: Very strong. Grows well at 37.5° C. Antagonistic properties: Represses growth of Streptomyces scabies. Relationship to other species: Krassil- nikov regards this species as being related to Streptomyces griseus Krainsky. Source: Isolated from a large, knob-like, unruptured potato scab. Habitat: Found in potatoes so far as known. 124. Streptomyces setonii (Millard and Burr, 1926) Waksman, 1953. (Actinomyces setonii Millard and Burr, Ann. Appl. Biol., 18, 1926, 601; Waksman, in Waksman and Lechevalier, Actinomycetes and Their Antibiotics, Baltimore, 1953, 107.) .se.to'ni.i. M.L. gen. noun setonii of Seton; named for a person, Seton. Vegetative growth: Golden yellow on synthetic media. Aerial mycelium: Well developed, cot- tony, dark gray to dark olive. Sporophores straight, forming few spirals. Spores ellip- soidal, 0.6 to 0.8 by 0.85 micron. Gelatin: Gray surface growth covered with white aerial mycelium. Soluble brown- ish pigment. Rapid liquefaction. Agar: Good, colorless growth covered with white, smooth aerial mycelium. Soluble brownish pigment. Sjmthetic agar: Abundant, smooth growth. Aerial mycelium covering the whole surface, gray to olive-buff. Soluble, faint yellowish pigment. Starch agar: Cream-colored growth. Aerial mycelium patch}', white. Glucose agar: Good, lichenoid, gray to brown growth. Aerial mycelium abundant, white to olive-buff. Soluble, golden brown pigment. Glycerol synthetic solution: Flak}', white growth. Aerial mycelium abundant, olive- buff. Soluble greenish pigment. Glucose broth: Growth on surface and in liquid good. Aerial mycelium abundant, olive-buff. Soluble, light golden brown pig- ment. Milk: Good surface growth covered with ring of white aerial mycelium. Coagulated, followed by rapid digestion. Potato: Heavy, wrinkled growth covered
