80 



THE ACTINOMYCETES, Vol. I 



cardia. Others are acid-fast to a variable 

 degree that depends both on the oi'ganism 

 and on the cultural conditions. 



According to Jensen, acid-fastness in 

 pathogenic forms is often stronger in vivo 

 than in vitro. Man}^ species can probably 

 best be described as potentially acid-fast, 

 because this property may be apparent for 

 only a very brief period in the organism's 

 life history and can be induced by special 

 media, like milk (Jensen, 1981-1934; Um- 

 breit, 1939) or synthetic media containing 

 paraffin or high concentrations of glycerol 

 (Eriekson, 1949). 



Acid-fastness is not a permanent property 

 of an organism. On continued cultivation on 

 ordinary media, the acid-fast characteristic 

 may be lost; on the other hand, the property 

 may be strengthened by growing the organ- 

 ism in media containing oil or fat or on 

 animal passage. Acid-fastness cannot be con- 

 sidered as a characteristic for species difTer- 

 entiation. 



Some of the observations of stained prep- 

 arations of actinomycetes have to do with 

 the presence in the thin cells of a nucleus and 

 other particulate constituents. Crystal violet 

 and thionine SO 2 , as well as crystal violet - 

 tannic acid-congo red cell wall stain, can be 

 used (Webl) and Clark). 



Lieske and others failed to observe any 

 true nucleus in actinomycete cells: nuclear 



'/ 



."i -,1 / .: 

 f'i ■'■•■ J 





Figure 40. Formation of coremia l)y a .st repto- 

 myces (Reproduced from: Krassilnikov, N. A. 

 "Manual of the ray funfii". Acad. Xauk, USSR, 

 Moscow, 1938, p. 34 J. 



sul^stance was found in the form of grains, 

 which, in Lieske's opinion, pointed to the 

 close relationship of these organisms to the 

 bacteria. 



The occurrence of fatty particles in the 

 cells of actinomycetes was observed by 

 \arious investigators. Glycogen and chitin 

 could not be foimd. 



Substrate Mycelium 



Actinomycetes produce a substrate or, as 

 it is often designated, vegetative mycelium 

 that usually varies in size, shape, and thick- 

 ness. The color of the substrate growth 

 ranges from whitish or cream to brownish, 

 yellow, red, pink, orange, green, or black. 

 Water-soluble and water-insoluble pigments 

 may be produced, depending on the organ- 

 ism and the composition of the medium. 

 Some of the pigments, especially the dark or 

 chromogenic pigments, are formed upon 

 complex organic media and are often a result 

 of the action of certain enzymes of the tyrosin- 

 ase type upon proteins and their deriva- 

 tives. Other pigments are synthetic in nature 

 and are formed on simple media. 



The spores of actinomycetes germinate in 

 the medium with the formation of one or 

 more germ tubes. These grow into long 

 hyphae, finally culminating in a complex 

 mycelium. The length and the diameter of 

 the hyphae differ considerably. Some are 

 straight and reach a length of more than 

 600 )Lt; others are only 50 to 100 n in length 

 and are much branched and curved. This 

 frecjuently suggested the division of acti- 

 nomycetes into long-mycelial and short- 

 mycelial groups. The vegetative mycelium 

 varies in diameter from 0.2 to 0.8 ju- The 

 branching of the mycelium is typically mon- 

 opodia!. Involution forms which have a 

 greater diameter may also be produced 

 ( IV r (inter, 1916). 



On continued growth, the vegetative my- 

 celium l)ecom(\s brittle and breaks into 

 fragments of uneven length. Some cultures, 



