LV'I'K" MIXIIAMSMS 



17!) 



DilTcriMit ]>h:ijj;os are ahlo to attack the 

 saincDi'jiaiiisin. Cultures of .S. (jrisciis iikuIc 

 ivsistant to one type ot phat^c may in lime 

 hocoinc s(Misitivr to anotluM". The tonnation 

 of lysoticnic strains coutaininfj; a prophage 

 \vas(l(Mnoiistrat(>(l hy Wclscii (n)o4). Wolsch 

 (I!>.")7) further cltMuonst rated that se\eral ac- 

 tinophages can \)v found in a singh^ natural 

 substrate. They differ in the niorpholojiy of 

 their jihuiues. their host-ranji;e, and their an- 

 tigenic projierties. A gi\"en a('tinophag(> may 

 he presiMit in its natural hai)itat in a concen- 

 tration of 1(F to 10^ particles ml. 



.V search was made for truly lysogenic 

 streptomyces. Thymol-st(M'iliz(>d cultui'c flu- 

 ids of \-arious organisms were tested upon 

 many indicator strains. About 15 per cent of 

 the organisms freshly isolated from a natural 

 substrate or taken from a collection of cul- 

 tures actually carried a phage. The true lysog- 

 eiiy of this phenomenon was demonstrated 

 by the constancy of the ratio of phage to 

 streptomj'ces in different cultures, and by the 

 maintenance of phage production after re- 

 peated single colony isolation or serial culti- 

 vation in a medium containing a specific an- 

 tiphage serum. 



The theoretical and practical significance 

 of lysogenesis among actinomycetes has been 

 discussed by Rautenstein (1957). The phe- 

 nomenon of true lysogeny was found to be 

 widely distributed among the actinomycetes. 

 As many as 53 per cent of the *S'. olivaceus 

 cultures examined possessed that propertJ^ 

 Numerous other species proved to be h'so- 

 genic, including *S'. diastaticus, S. cacaoi, S. 

 candidus, S. griseus, S. autibiolirxs, and S. 

 scabies. 



Many of the lysogenic actinomycetes eas- 

 ily liberate the phage when grown as sub- 

 merged cultures for 48 hours on a shaker. In 

 a studj' of their mutual infhience, the lyso- 

 genic state of a series of actinomycetes was 

 demonstrated by juxtaposing agar blocks 

 bearing certain cultures on the sujjerficial 

 growth layer of others. Some of the lysogenic 



cultui'es contained \-aiMous ])hages with dif- 

 fei'ent lytic i)roperties. 



All indicator cult ure was used to i-cxcal the 

 de\-elopment of the phage of the lys(»genic 

 culture. It often influenced the lytic proper- 

 ties of a gi\('n phage. This infiuence became 

 partitailarly significant when the inchcator 

 cultui-e was itself lysc^genic. I'hages which 

 ha\'e the faculty to cause lysis of their own 

 (ailture wei'c often isolated from lysogenic ac- 

 tinomycetes. This suggested that many acti- 

 no])hages are able to change their lytic 

 ])i-op(M'ty more or less easily. 



Some phage-resistant variants obtained 

 exi)erimentally differed from their initial cul- 

 tures in their antibiotic properties. Many of 

 tliese variants were found to be lysogenic. 

 The possibility was .suggested that accjuisi- 

 tion of new antibiotic properties may be con- 

 nected with lysogenization. 



Uautenstein suggested that the broad dis- 

 tribution of l.ysogeny among actinonwcetes 

 and the diverse character of changes caused 

 by actinophages in corresponding sensitive 

 cultures influence the variability and the 

 evolution of the actinomycetes in an impor- 

 tant manner. The disli'ibution of lysogenic 

 actinom^'cetes in nature has been studied 

 further by Bradley. 



The isolation of actinophage from soil has 

 been studied by Rautenstein and Kofanova 

 (1957), Khavina and Rautenstein (1958), 

 and others. S. olivaceus actinophage has been 

 isolated from greenhouse soil; it proved spe- 

 cific for cultures of S. olivaceus. It was sug- 

 gested to use this actinophage for the identi- 

 fication of cultures of this species. Out of 17 

 S. olivaceus cultures tested, 9, or 53 per cent, 

 proved Ij^sogenic. The actinophages isolated 

 from these cultures proxcd identical to one 

 another and somewhat ditferent in their lytic 

 jiroperties from the phage isolated from the 

 soil. 



S\-eshiiiko\a and Pariskaya made a de- 

 tailed examination of the occurrence of actin- 



