64 



THE ACTINOMYCETES, Vol. I 



name Microhispora, with the type species 

 M. rosea. These investigators proposed divi- 

 sion of the family Streptomycetaceae as fol- 

 lows : 



I. Spores formed in chains from aerial 

 hyphae Streptomyces 



II. Spores formed in pairs on aerial 

 hyphae Microhispora 



III. Spores formed singly on sporophores. 



1. Mesophilic Micromonospora 



2. Thermophilic. .Thermoactinomyces 



IV. Sclerotic granules produced (conidial 

 forms unknown) Chainia 



According to Henssen (1957), the majority 

 of thermophilic actinomycetes thrive better 

 under anaerobic than under aerobic condi- 



FiGURE 32. Waksmania rosea {Microhispora 

 rosea), showing tho formation of pairs of spores 

 either directly on the spore-hearing hyphae or on 

 short side branches (Reproduced from: Lecheva- 

 lier, M. P. and Lechevalier, H. J. Gen. Microbiol. 

 17: 104, 1957). 



tions; they may, therefore, be designated as 

 facultative aerobes. The preference for 

 anaerobic conditions varies with the species, 

 especially in the case of freshly isolated cul- 

 tures. When originally isolated under exclu- 

 sion of oxygen, cultures grow well later also 

 in presence of oxygen, but only at optimum 

 temperature. Production of aerial mycelium 

 is closely bound to optimum temperature. 

 For example, Thermopolyspora bispora grows 

 and produces aerial mycelium at 50 to 60°C 

 under aerobic and anaerobic conditions; 

 below that temperature, growth takes place 

 only under anaerobic conditions; at 70°C, 

 growth is good but aerial mycelium and 

 spores are no longer produced. 



Henssen proposed division of the family 

 Streptomycetaceae into the following genera, 

 taking into consideration the thermophilic 

 forms : 



A. Substrate mycelium nonseptate, spores pro- 



duced on aerial or substrate mycelium. 

 I. Spores produced on substrate mycelium, 

 mesophilic forms 



Micromonospora 0rskov 

 II. Spores produced on aerial mycelium. 



1. Aerial hyphae develop only as side or 

 terminal branches of the substrate 

 mycelium. 



a. Aerial hyphae are formed as long 

 chains of spores, mesophilic or ther- 

 mophilic forms 



Streptomyces Waksman and Henrici 



b. Spores and sporophores produced on 

 the unbranched aerial hyphae. 



a'. Spores single, thermophiles 



Thermonospora Henssen 



b'. Spores in short chains 



Thermopolyspora Henssen 



2. Aerial hyphae develop as side, terminal, 

 and arched-shaped branches of the sub- 

 strate hyphae growing out of the agar, 

 thermophilic forms 



Thertnoactinotnyces Tsiklinsky 



B. Substrate mycelium septate, spores formed 



from the aerial and from the substrate ni}-- 

 celium, thermophilic 



Pseudonocanlia Henssen 



New genera, as well as mnnerous species, 

 have thus ])ecn added at an ever-increasing 



