Description of 



Species of Thermoactinomyces 



1. Thermoactinomyces vulgaris Tsiklinsky. (Tsiklinsky, P., Ann. 

 Inst. Pasteur, IS, 1899, 500.) 



Vegetative growth: Good growth on organic and synthetic media. My- 

 celium 0.5 m in diameter. No soluble pigment. 



Aerial mycelium: White, powdery. Spherical and oval spores are borne 

 singly at the ends of short branches, from which they are easily broken. 



Synthetic agar: Growth colorless, covered with white aerial mycelium. 

 Sporophores very short, not exceeding 2 ju in length, often only 0.5-1.0 /x. 

 Spores oval or spherical, often appear to sit directly on mycelium. 



Nutrient agar: Good growth, producing aerial mycelium. 



Potato: Growth good. 



Gelatin: Liquefaction positive. 



Milk: Coagulation and peptonization. 



Starch: Hydrolysis positive. 



Cellulose: No decomposition. 



Nutrient broth: Growth in form of white pellicle and often as compact 

 balls on bottom of culture. 



Nitrate: No reduction. 



Sucrose: No inversion. 



Temperature: Grows at 48° to 68°C; optimum at 57°C. 



Source: Human and animal excreta, high temperature composts, self- 

 heated hay, soil. 



2. Thermoactinomyces monospora (Lehmann and Schiitze emend. 

 Jensen), comb. nov. (Schiitze, H., Arch. Hyg., 67, 1908, 35; after Krassilni- 

 kov, 1941.) 



Vegetative growth: Good growth in various media; yellowish, compact, 

 smooth or lichnoid. Hyphae about 1.0 ju in diameter. 



Aerial mycelium: Well-developed, covering the whole growth, grayish 

 green. Good sporulation of hay infusion-peptone agar; somewhat less on 

 glycerol-peptone and lactose-peptone agar; none on peptone-glucose agar. 

 Oval spores, 1.5-1.8 by 1.0-1.4 n, produced on simple short sporophores. 



Potato: No growth. 



Gelatin : Liquefaction positive. 



Milk: No coagulation. 



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