Actinomycetes 



79 



The aerial nneeliuin may be white, gray, laxeiider, red, yellow, 

 brown, green, or of some other type of pigmentation. The aerial 

 hyphae may be short, giN'ing the growth a chalky appearance, or long, 

 forming a thick mat o\er the snrface of the vegetative growth; or 



Fig. 35. Soil actinomycetes showing difPerent types of sporulation. 



they may form a fine network. The colonies are often brilliantly 

 colored. Some cultures produce soluble pigments which vary in 

 color and intensity in accordance with the effect of the composition 

 of the medium. Most species are characterized by the production of 

 a peculiar sharp odor, characteristic of the soil (earthy odor). All 

 species of Streptomyccs liquefy gelatin; the rapidity of liquefaction 

 depends upon the nature of the organism and previous cultivation. 

 Most of the actinomycetes produce acti\e diastatic enzymes; fewer 

 produce invertase; still fewer produce tyrosinase, which enables 



