CHARACTERIZATION OF STREPTOMYCES SPECIES 



SI 



.">. Analysis of certain physiological and 

 biochemical properties, notably action on 

 gelatin, starch, milk, and peptone-iron agar; 

 nitrate reduction; utilization of carbon and 

 nitrogen compounds; antibiotic action, com- 

 prising formation of and sensitivity to anti- 

 biotics. 



6. Identification of new strains with 

 known species, and preservation of cultures. 



Pridham* emphasized that recently lie has 

 been placing principal emphasis on micro- 

 morphology, secondary emphasis on chro- 

 mogenicity (deep brown to black diffusible 

 pigments), and tei't iary emphasis on color of 

 aerial mycelium. 



In an effort to determine whether freshly 

 isolated cultures can he identified on the 

 basis of published descriptions and what con- 

 ditions justify the creation of new species, 

 several obvious comparisons were made 

 (Waksman, li>o7). Certain strains that 

 mighl he included in various important 

 species or ^roup-species were critically ex- 

 amined. The following conclusions were 

 reached: 



At present, various morphological, cultural, 

 and biochemical properties arc know a which make 

 it possible t<> establish definitely certain distinct 

 species among the actinomycetes. Some of these 



characters are constant within certain conditions 

 of nutrition and environment, others are varia- 

 ble. Certain additional properties may he re- 

 quired in order to establish the degree of varia- 

 tion of ;i culture before it can lie recognized as a 

 neu species. 



Certain categories of relationships among the 

 actinomycetes must be taken into consideration 

 in order to establish definitely the systematic 

 position of a given culture. These may lie briefly 

 summarized as follow a : 



1. On I he basis of all the accumulated evi- 

 dence, actinomycetes are shown to belong defi- 

 nitely to t he bacteria. 



2. The position of the true act i nom vcet es in 



relation to related bacteria] forms, aotably the 

 * Personal communical ion. 



mycobacteria and corynebacteria, musl be recog 

 ni/i'il; this is true especially of certain aocardial 

 types 



3. The generic interrelationships among the 



actii ycetes are highly significant. The separa 



tion <)f members of the genus Streptomyces from 

 those of Nocardia is difficult, especially when one 

 is dealing with nonsporulating forms of the first 

 nml sporulating forms of the second. The recent 

 addition of two new genera, Actinoplanes and 

 Streptosporangium, and the recognition of certain 

 thermophilic groups as separate genera add fur- 

 ther problems to these generic interrelationships. 



4. Within each genus, certain groups, species 

 groups, or series must he recognized. A combina- 

 tion of morphological and cultural properties 

 permits the establishment of species-groups. 

 Some of these comprise a large number of forms 

 with many variable characteristics. 



5. Differentiation of individual species within 

 each group is based upon a combination of cul- 

 tural and biochemical properties. The production 

 of specific antibiotics and the utilization of differ 

 cut sugars are ample illustrations of this. 



ti. Cognizance of the strains and varieties 

 within each species musl finally he taken. This 

 may he based upon certain qualitative properties, 

 such as sensitivity to phages, or quantitative 

 properties, such as production of a given anti 

 biotic, vitamin, or enzyme, or sensitivity to a 



given ant ihiot ic. 



The fact that a culture becomes important 

 for the production of a particular metabolic 

 product, such as an antibiotic, an enzyme, 

 or a vitamin, may impart to the culture 

 particular significance for characterization 

 purposes. 



The existence of physiologic races or varie- 

 ties among species of actinomycetes, espe- 

 cially among those placed in the genus 

 Streptomyces, has been fully recognized. 

 Just as in improving higher form- of life 

 one is always faced witli the selection of 

 variet ies resistant to disease, or giving higher 

 yields, or having other desirable qualities, 

 so one must select strain.- of actinomycetes 

 on the hasis of resistance to phage or of pro- 

 duct ion of higher yields of a given antibiotic 

 or other metabolic product . 



