36 ACTINOMYCETES 



b 1 . Cultures green; spores black or brown. 



Micromonospora bicolor 

 c 1 . Pigment not excreted into substrate. 



Micromonospora parva 

 d 1 . Red-brown pigment excreted into substrate, spores dark 

 brown. 



Micromonospora fusca 

 B. Sporophores short, branched. 



I. Spores elongated. .Micromonospora monospora 

 II. Spores oval or spherical. 



1. Cultures colorless; spores in mass white. 



Micromonospora vulgaris 



2. Cultures brown; spores dark brown. 



Micromonospora elongata 



Classification System of Jensen (emend.) 



A. Vigorously growing organisms, with copious spore formation. 



I. Vegetative mycelium pale pink to deep orange; no typical soluble 

 pigment. 



1. Micromonospora chalcea 



II. Vegetative mycelium orange, changing to brownish black; soluble 

 pigment brown. 



2. Micromonospora fusca 



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

 glucose-asparagine agar; no soluble pigment. 



I. Vegetative mycelium pale pink to pale orange. 



3. Micromonospora parva 

 II. Vegetative mycelium yellow to orange-red. 



4. Micromonospora globosa 

 III. Vegetative mycelium blue. 



5. Micromonospora coerulea 



The Genus Thermoactinomyces 



The genus Thermoactinomyces is in some respects similar to Micromono- 

 spora, especially in its ability to produce single conidia at the tips of simple 

 or branching conidiophores, which may be so short that they often appear 

 to be produced directly on the mycelium. In other respects, notably in 

 appearance and in its ability to produce a true aerial mycelium, this genus 

 resembles Streptomyces. It comprises so far only thermophilic forms capable 

 of growing at 50°-65°C. Some have their optimum at 60°C. Three species 

 have so far been recognized. 



