Synthetic glycerol agar: Colorless to brownish, restricted growth. Scant white to dark grayish colored aerial mj^celium. Soluble brown pigment. Egg media: Reddish brown, wrinkled growth. No aerial mycelium. No soluble pigment. Loeffler's blood serum: Elevated, wrinkled, colorless to brownish growth. No aerial mycelium. No soluble pigment. No liquefaction. Blood agar: Brownish, wrinkled, poor growth. No aerial mycelium. No soluble pigment. No hemolysis. Milk: Poor surface growth. No aerial mycelium. No soluble pigment. Coagulated and slowly peptonized. Potato plug: Yellowish brown to brown- ish, fine, wrinkled growth. White, powdery aerial mycelium. No soluble pigment at first, later reddish brown. Nitrites produced from nitrates. Antagonistic properties: Produces an antiviral agent, achromoviromycin. Distinctive characters: This species re- sembles Sfreptomyces diastaticus and Strep- tomyces fimicarius. This species differs from the former in spiral formation, hemolysis, liquefaction of gelatin and proteolj^tic ac- tion of milk. It differs from the latter in the liquefaction of coagulated serum. This species is characterized by the brown pig- mentation on synthetic agar only. Source: Isolated from garden soil at Suginami-ku, Tokyo. Habitat: Soil. 39. Streptoniyces noursei Brown et al., 1953. (A soil actinomycete, Hazen and Brown, Science, 112, 1950, 423; Streptoniyces sp. No. 48240, Hazen and Brown, Proc. Soc. Exp. Biol, and Med., 76, 1951, 93; Brown, Hazen and Mason, Science, 117, 1953, 609.) nour'se.i. M.L. gen. noun noursei of Nourse; named for the owner of the farm where the soil sample was obtained from which this organism was isolated. Description prepared by Hazen and Brown for use in Waksman and Lechevalier, Actinomycetes and Their Antibiotics, Baltimore, 1953. Vegetative growth: Good growth, gray to brown, much folded on various organic and certain synthetic media. Soluble pink to purple pigment frequently produced. Aerial mycelium: Well developed, white to shell-pink. Straight, curved and spiral- forming sporulating hyphae. Round to el- lipsoidal spores. Gelatin: Rapid liquefaction. Synthetic agar: Scant, colorless, flat growth. No aerial mj^celium. Glucose asparagine agar: Wrinkled, tan growth with gray and white knob-like pro- jections. Dark gray reverse. At 35° to 36°C., scant, shell-pink aerial mycelium; limited, shell-pink soluble pigment. Starch agar: Good growth in form of dis- crete colonies with white aerial mycelium in center and periphery colorless and em- bedded. Glucose agar: Good, folded growth. White aerial mycelium, turning gray. Re- verse of growth brown, medium often be- coming darkened throughout. Occasionally pomegranate-purple soluble pigment is formed. Blood agar: Good growth, consisting of convex, lobate colonies with central perfora- tion. Aerial mycelium heavy, chalky white. No hemolysis, but darkening of blood. Honey broth: Heavy white ring on sur- face; flocculent sediment. Broth clear. Milk: Coagulated then peptonized. Potato: Good, folded growth with chalky white aerial mycelium. At 35° to 36° C, a reddish purple pigment is formed. Starch is hydrolyzed. Poor growth on cellulose. Nitrites weakly produced from nitrates. Antagonistic properties: Produces an antifungal agent, nystatin, which is active against various yeast-like and filamentous fungi, and an antibacterial agent, phala- mycin. Source: Isolated from soil from Fauquier County, Virginia. Habitat: Soil. 40. Streptoniyces roseochromogenes (Jensen, 1931) Waksman and Henrici, 1948. (Actinomyces roseus Krainsky, Cent. f. Bakt., II Abt., 41, 1914, 662; also see Waks- man and Curtis, Soil Sci., 1, 1916, 125; and Waksman, Soil Sci., 8, 1919, 148; not Acti-
