THKRMol'HII.lC A.CTINOMYCETES 



309 



at 45°C. The organism in many ways re- 

 sembles Tkermoactinomyces monosporus. The 

 points of difference, however, arc considered 

 significant, the latter possessing hyphae 

 with a diameter of about 1 m, an optimum 

 growth range of 37 to 55°C, and failing to 

 coagulate milk. 



(i. Thermoactinomyces vulgaris Tsiklinsky, 

 L899 (Tsiklinsky, P. Ann. inst. Pasteur Pi: 

 500, 1899). 



Synonym: Micromonospora vulgaris Waks- 

 man et aL, 1939; Erikson, 1953. 



Morphology: Substrate mycelium fine, 0.5 

 ft in diameter. Spherical and oval spores are 

 borne singly at the ends of short branches, 

 from which they are easily broken. They 

 often appear to sit directly on mycelium. 



Sucrose nitrate agar: Growth colorless. 

 Aerial mycelium white. 



Nutrient agar: Growth good. Aerial my- 

 celium white. 



Potato: ( Irowth good. 



Gelatin: Liquefaction positive. 



Milk: Coagulation and peptonization. 



Starch: Hydrolysis positive. 



Cellulose: No decomposition. 



Nitrate reduction: Negative. 



Sucrose: Not inverted. 



Temperature: Grows at 18 68°C; opti- 

 mum at 57°C. 



Source: Human and animal excreta, high 

 temperature composts, self-heated hay, soil. 



Remarks: Resembles mesophilic members 

 of the genus Micromonospora, except that it 

 produces an aerial mycelium which forms 

 single spherical spores. The aerial phase of 

 the development of this organism is believed 

 to be intimately associated with its thermo- 

 philic nature (Erikson, 1952, 1953, 1955a). 

 Oxygen concentration has an important 

 effect upon the growth of the aerial mycelium 

 of this organism (Webley, 1954). The effect 

 of composition of medium and the growth- 

 temperature relationships of this organism 

 were sttidied recently by Tendler (1959). 



Pseudonocardia 



Substrate mycelium septated. Spores pro- 

 duced in substrate and in aerial mycelium. 



On the basis of its morphology, Pst udo- 

 nocardia should be placed between Strepto- 

 myces and Norcardia. Along with Nocardia, 

 it has the common property of septal ion of 

 the substrate mycelium, but no fragmenta- 

 tion. In common with Streptomyces, it pro- 

 duces aerial mycelium which is thicker than 

 the substrate mycelium, and which changes 

 into long spore chains. It differs from Strep- 

 tomyces in being unable to hydrolyze gelatin 

 or starch. 



Type species: Pseudonocardia thermophila 

 Henssen. 



Pseudonocardia thermophila Henssen, 1957 

 (Henssen, A. Arch. Mikrobiol. 26: 373-414. 



1957). 



Morphology: Substrate mycelium sep- 

 tated. Spore formation in substrate myce- 

 lium. Aerial hyphae unbranched, formed as 

 side branches of the substrate hyphae. 

 Spores basipetal. Substrate spores 2.5 by 

 1.5 to I.S fji. Aerial spores produced in chains 

 at the tip of the hyphae are 2.5 n long; spores 

 produced at the base of the chain are 5 ju 

 long by 1.5 to l.S ^ wide. Thermophilic, 

 facultative aerobe (Fig. 62). 



Sucrose nitrate agar: Growth yellow. 

 Aerial mycelium limited, while. 



Glycerol-asparagine agar: Growth moder- 

 ate, yellow. Aerial mycelium produced, 

 white. 



Nutrient agar: Growth good, yellow. 

 Aerial mycelium in thick colonies. 



Potato: Colonies individual, yellow. No 

 aerial mycelium. Soluble pigment yellow. 



( ielatin : Not liquefied. 



Starch: No hydrolysis. 



Nitrate reduction : Positive. 



Milk: Unchanged in Hi days. 



Habitat : Fresh horse manure. 



