M()|;i'ii()1,();;n , ('^'l'()l,(»(;^ , and i.iki-: ('^■('IJ•:s 



77 



FlGiRE 37. Sporuliition of .S. r///.s('//.s (Rpprodufed from: Haldacci, K. and (Irciii, A. (Jiorn. Micro- 

 biol. 1: 34. 1955). 



crosc'ope, the edge of the colony shows a 

 characteristic picture of radiating hyphae. 

 Wlien grown in liiiuid niecUa in a stationary 

 condition, the colonies may be formed in- 

 dividually on the bottom of the container, 

 or they may adhere to the surface of the wall, 

 or they may form a ring of growth or a pelli- 

 cle on the surface. The colonies may also 

 grow in the form of flakes, but the medium 

 is never made turbid, as in the case of l)ac- 

 tei'ial growth, unless the colonies undergo 

 lysis through the action of enzymes or 

 phages. When grown in a submerged or in 

 a .shaken condition, actinomycetes produce 

 small, bead-like masses of growth, some of 

 which may l)e granular in natui'e. 



According to Jen.sen, strains of Xoranlia 

 with more persistent mycelium produce firm 

 agar colonies and a discretely graiuilar 

 growth in licjuid media, which remain clear; 

 those with small or rapidly dixiding myce- 

 lium show a soft growth in solid media and a 

 diffuse, bacterium-like growth in liquid 

 media. Jensen took exception to Lieske's 

 (1921) .statement that "every form of tur- 

 bidity of a li{[uid medium is to be looked 

 upon as evidence of contamination." He also 



pointed out that a similar difference exists in 

 cultures of the genus Actinomyces, where 

 most strains show a granular growth V)ut 

 some gi\'e a clcjudy growth in broth (Erik- 

 son, 1940; Holm, 1948). The colonies of the 

 bovine strains of this anaerobic genus Actino- 

 mijcc's are smooth and soft in consistency and 

 do not adhere to the medium; the mycelium 

 undergoes fragmentation very rapidly, giv- 

 ing no extensive ramification; .such strains 

 show occasional turl)idity in the medium. 

 In contrast, hun;an strains give no stable 

 variants and produce no turbidity (Erik.son). 

 Various attempts have been made to 

 divide the actinomycetes into groups on the 

 basis of the size of the colonies (Krainsky) 

 or the length of hyphae (Lieske). These 

 propei'ties are not recognized now as of pri- 

 mary significance in classification, since the 

 nature of the organisms and the conditions 

 of growth are of prime importance. 



Staining Properties 



The mycelium of the actinomycetes can 

 be dried on slides and stained with ordinary 

 aniline dyes. Methyl violet, carbol-fuchsin, 

 and methvlene blue can be used. Fresh my- 



