Waksman — 32 — Actinomycetes 



conidiophores, on surface of substrate mycelium. Conidiophores short 

 and simple, branched, or produced in clusters. Strongly proteolytic 

 and diastatic. Comprise mostly saprophytic forms. These organisms 

 occur commonly in hot composted manure, in aerial dust, and in soil, 

 in river and lake waters, and in river and lake bottoms. Many are 

 thermophilic and can grow at 65 °C. 



Key to the species of the genus Micrmnonosfora:— 



I. Vigorously growing organisms, typically copious spore formation on dextrose- 

 asparagine agar. 



A. Vegetative mycelium pale pink to deep orange, no typical soluble 

 pigment 1. Micromonospora chalcea. 



B. Vegetative mycelium orange changing to brownish-black, brown soluble 

 pigment 2. Micromonos'pora ftisca. 



II. Slowly and feebly growing organisms, with scant spore formation on 

 dextrose-asparagine agar, no soluble pigment. 



A. Vegetative mycelium pale pink to pale orange 



3. Micromonosfora parva. 



B. Vegetative mycelium yellow to orange-red 



4. Micromonospora glohosa. 



C. Vegetative mycelium blue 5. Micromonospora vulgaris. 



Type Species: Micromonospora chalcea (Foulerton) Orskov. 

 CStreptothrix chalcea Foulerton; Nocardia chalcea Chalmers and Chris- 

 topherson; Actinomyces chalcea Ford). 



Formation of a unicellular mycelium which produces distally placed, 

 singly situated spores. No aerial hyphae. No surface growth in liquid 

 medium. The organism absolutely resists desiccation for at least 8 

 months. Comparison between the power of resistance of the mycelium 

 and the spores, respectively, will no doubt present great difhcultv, be- 

 cause it is almost impossible to ensure that the two constituents are ac- 

 tually detached. Otherwise, the mycelium is but slightly capable of 

 germinating, which may be ascertained by inoculating a water-agar plate 

 liberally with a mixture of mycelial threads and spores. Though virtu- 

 ally all the spores germinate, the mycelial threads have never been 

 found to form new colonies. 



According to Jensen, vegetative mycelium on dextrose-asparagine- 

 agar is heavy, compact, raised, not spreading much into the medium. 

 Spore layer well developed, moist and glistening, brownish-black to 

 greenish-black, this color sometimes spreading through the whole mass 

 of growth. 



Liquid media: Growth in form of small, firm orange granules or flakes. 

 Starch: Starch is hydrolyzed. 

 Gelatin: Liquefied. 



Milk: Digestion of milk with a faintly acid reaction, mostly after a previous 

 coagulation. 



