95 



THE ACTINOMYCETES. Vol. II 



Recent Systems of Classification 



Several systems for classifying species 

 belonging to the genus Streptomyces have 

 recently been proposed. Some of these have 

 been selected for detailed examination. They 

 aie based largely upon morphology, cultural 

 and biochemical properties, or combina- 

 tions of these. 



1. HESSELTIXE, BENEDICT, AND PRIDHAM 

 SYSTEM (1954) 



In this system, emphasis was laid upon 

 morphology as the basis for separation of 

 the genus into five basic groups. After a 

 study of hundreds of cultures on a variety 

 of media, the conclusion was reached that 

 the morphology of any one strain of Strepto- 

 myces is essentially the same on any medium 

 where sporulation occurs. The major groups 

 were subdivided into a number of subgroups 

 on the basis of cultural properties, pigmen- 

 tation of spores, and other criteria. 



I. Sporophores not restricted in length, 

 bearing fertile branches in verticils, 

 with spores more or less strongly at- 

 tached. 



1. Fertile branches in simple verticils, 

 branches not ending in spirals. 



2. Fertile branches in simple verticils, 

 branches ending in spirals. 



3. Fertile branches with compound 

 verticils, branches not ending in 

 spirals. 



II. Sporophores with branches all straight, 

 never ending in spirals; verticils ab- 

 sent. 



III. Sporophores predominantly in tufts, 

 never verticillate; outline of branches 

 flexuous and irregular. 



IV. Sporophores with branches ending in 

 spirals, verticils being absent; sporo- 

 phores either as long stalks bearing 

 very short branches, or as short stalks 

 bearing branches irregularly. 



1. Branches ending in open spirals with 

 many turns. 



2. Branches ending in closed spirals- 

 wit h few turns, thus appearing as 

 tight knots. 

 V. Sporophores with long and straight 

 branches with spirals of large diameter 

 at their ends; spiials usually with only 

 a few turns, never verticillate. 

 Xo strains were observed in which the 

 sporophores were unbranched, except when 

 they were growing under unfavorable con- 

 ditions oi- where degenerated type cultures 

 were studied. 



Seven major Streptomyces groups were 

 thus created as indicated by the following 

 key: 



I. Sporophores produce verticils; spores not 

 readily separating; aerial mycelium white, 

 pink, lavender, or tan. 



Group I. Streptomyces reticuli 



1. Verticil branches simple. 



a. Sporophores straight. 



b. Sporophores spiral-shaped. 



2. Verticil branches compound. 



a. Ultimate branches straight. 



b. Ultimate branches spiraled. 



II. Sporophores not producing any verticils; 

 spores readily separate; color of aerial myce- 

 lium often not pink, white, lavender, or tan. 



1. Spirals always formed; color of aerial my- 

 celium blue, blue-green, or green. 



Group II. Streptomyces viridochro- 

 mogenes 



2. Spirals may or may not be formed; color of 

 aerial mycelium different . 



a. Spirals never formed, tufts often present ; 

 color of aerial mycelium greenish-tan or 

 tan. never white. 



Group III. Streptomyces griseus 

 1). Spirals produced; color of aerial myce- 

 lium lavender, red, pink, or nearly tan. 

 Group IV. Streptomyces lavendulca 



3. Sporophores straight . 



a. Sixties white or nearly so. 



Group V. Streptomyces albus 



b. Aerial mycelium never white. 

 a 1 . Aerial mycelium yellow. 



Group VI. Streptomyces parvus 

 b 1 . Aerial mycelium gray, gray-brown, 

 olive-gray, blackish-gray. 

 Group VII. Gray-spored group. 



It was suggested that the last group could 



