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THE ACTINOMYCETES, Vol. II 



or from soil. It inhibits spreading bacteria 

 and favors the production of a dark brown 

 pigment closely encircling colonies of the 

 pathogen. Since almost all pathogenic iso- 

 lates of S. scabies produce a dark pigment, 

 the selection of the probable pathogen from 

 dilution plates containing other actinomy- 

 cetes is favored. 

 / /. Peptone-beef extract or nutrient agar: 



Peptone 5.0 gm 



Beef extract 5.0 gm 



NaCl 5.0 gm 



Agar 15 to 20 gm 



Distilled water 1000.0 ml 



pH 7.2 to 7.4 

 Frequently 10 gm of peptone is used. Glu- 

 cose (10 gm) or glycerol (15 gm) may be 

 added to give glucose- or glycerol-peptone 

 agar. Tap water is often used in place of 

 distilled water. In a liquid state without 

 agar, these media are designated as nu- 

 trient broth, glucose-peptone broth, or glyc- 

 erol-peptone broth, respectively. 

 to. Peptone-beef -salt agar: 



Glucose 10.0 gm 



Peptone 5.0 gm 



Beef extract 5.0 gm 



K 2 HP0 4 1.0 gm 



MgS() r 7H,() 0.5 gm 



KC1 0.5 gm 



Agar 15.0 gm 



Distilled water 1000. ml 



The organic nutrients may be reduced to 

 one half or even one tenth of above concen- 

 tration, in order to favor production of aerial 

 mycelium in some cultures of actinomycetes. 



16. Glycerol-peptone-beef agar: 



Glycerol 20.0 gm 



Peptone 5.0 gm 



Beef extract 3.0 gm 



Agar 15.0 gm 



Distilled water 1000.0 ml 



pH 7.0 



17. Tryptone-yeast agar: 



Tryptone 1.0 gm 



Yeast extract 1.0 gm 



NaCl 8.5 gm 



Agar 17.0 gm 



Tap water 1000.0 ml 



18. Glucose-yeast-ammonium agar: 



Glucose 10.0 gm 



Yeast extract 1.0 gm 



(XH 4 ) 2 HP0 4 1.0 gm 



KC1 1.0 gm 



MgS0 4 -7H 2 0.2 gm 



Agar 15.0 gm 



Distilled water 1000.0 ml 



pH 7.0 



19. Gelatin media: 



Gelatin 100-200 gm 



Tap water 1000.0 ml 



Adjust to pH 7.4 



Sterilize 30 minutes at 110°C 

 This medium may be supplemented with 



glucose (20.0 gm) and peptone (5.0 gm) to 

 give glucose-peptone gelatin. 



20. Gelatin agar medium: 



Peptone 5.0 gm 



Beef extract 3.0 gm 



Gelatin 4.0 gm 



Agar 15.0 gm 



Distilled water 1000.0 ml 



pH 7.0 



21. Starch agar: 



Soluble starch 10.0 gm 



XaXO:; 1.0 gm 



KoHPO, 0.3 gm 



XaGl 0.5 gm 



MgG<) :! 1.0 gm 



Agar 1 5 . gm 



Distilled water 1000.0 ml 



CaC0 3 (3 gin) and MgS( ), ■ 7II,< ) (1 gm) may 



replace the MgC0 3 . (XII,),.S( ), (2 gm) or 

 asparagine (0.05 gm) may be used to replace 

 the nitrate. 



22. Starch-casein agar: 



Soluble starch 10.0 gm 



Casein (dissolved in XaOH) 1.0 gm 



Iv.IIPO, 0.5 gm 



Agar 1 5 . gm 



Water 1000.0 ml 



pH 7.0 to 7.5 



