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THE ACTINOMYCETES, Vol. II 



node, thus forming a "verticil," frequently 

 referred to as a "whorl." Very often the 

 sporophores may be branched toward the 

 end of the sporulating-hyphae, giving the 

 appearance of a "broom shaped branch," 

 or may give rise to the formation of a 

 "cluster," which is to be distinguished from 

 a typical verticil of sporophores. The verti- 

 cils may be primary or secondary in nature. 

 Among the variations of a verticil is the 

 formation of tufts, when straight branches 

 are grouped together on the aerial hyphae. 



The formation and nature of the verticils 

 may be changed with the composition of the 

 medium, a phenomenon first reported by 

 Waksman and Curtis (1916) and more 

 recently by Nakazawa (1955) and Shinobu 

 (1955a). Both primary and secondary ver- 

 ticils may be formed in the same culture. 



Baldacci (1953) did not recognize this im- 

 portant series at all. He gave series recog- 

 nition to one of its members, S. rubrireticuli, 

 merely on the basis of its pigmentation. 

 Gause et al. (1957), following this example, 

 included in the "ruber" series one "tuft- 

 forming" organism, also on the basis of its 

 pigmentation. Later, however, Baldacci 

 (1958) suggested separation of the verticil- 

 producing organisms into a separate genus, 

 Streptoverticillium, as shown elsewhere 

 (Chapter 4, Volume I). 



Various investigators have used morphol- 

 ogy as a basis for series separation of the 

 genus Streptomyces. It is sufficient to list 

 here three of them. 



Shinobu (1955a) proposed division of the 

 genus as follows: 



1. Monopodial branching. This section has 

 been divided on the basis of spiral forma- 

 tion. 



2. Verticil formation: 



a. Nitella type. Typical radial branches 

 almost equal in length. No spirals 

 formed. S. reticuli is given as a typical 

 representative. 



b. Anitella type. Radial branches differ 



from each other. Spirals formed with- 

 out proper radial symmetry. S. virido- 

 chromogenes is representative. 

 The S. reticuli subgroup was further di- 

 vided into: 



A. Verticils only primary. Sporophores straight. 



Streptomyces verticillatus 

 Streptomyces hiroshimensis 



B. Verticils both primary and secondary. Sporo- 

 phores form spirals. 



I. Colorless to brownish growth on synthetic 

 media. 



1. Good growth on protein media. Spores 

 spherical, oval. 



Streptom yces reticuli 

 Streptomyces albi reticuli 



2. Poor growth on protein media. Spores 

 cylindrical. 



Streptomyces circulatus 

 II. Growth on synthetic media pink to red. 

 Streptomyces reticuloruber 

 Streptomyces griseocarm sus 

 III. Growth on synthetic media greenish. 

 Streptomyces verticilloviridans 



Solovieva et al. (1957) made a study of 

 cultures belonging to the S. reticuli series 

 and isolated from Pamir soils. These cultures 

 were divided into two subgroups: 

 I. S. verticillatus, with straight sporophores 

 (primary and secondary). 

 II. S. reticuli, with spiral-shaped sporo- 

 phores. 



These subgroups showed very little dif- 

 ference in their physiological and biochem- 

 ical properties. Only one strain, S. rubri- 

 reticuli, showed some differences (weaker 

 gelat in liquefaction, strong nitrate reduction, 

 weak growth on cellulose). From an anti- 

 biotic point of view, however, there was a 

 marked difference; members of the first sub- 

 group showed strong antifungal activity, 

 whereas subgroup 11 gave weaker activity 

 or none. 



Pridham et al. (1958) divided the verticil- 

 forming series into four morphological sub- 

 groups: 



1. Monoverticillate, no spirals. 

 '2. Monoverticillate, with spirals. 



