I.VrK" MIX'llAMSMS 



U|)()ii ;i (It'filiitc ciiiupoiKMil (if the ti;i('t("ri;il 

 cytuplasin, access to wliicli is jxissiMc only 

 after disruption of the cell \v;ill, as seems to 

 \)0 tlu> eas(^ t'oi' trypsin. 



S\V(M"t/, niadi^ a study of the phenomenon 

 of halo t'ormation in the pi'ocess of hactei-io- 

 lysis hy actinomycetos. When llie actinomy- 

 cetes were grown on l)aet(M'ial \vat(M- a.uar 

 plates (usiuo; heat-killed h\ coli and heat- 

 killed or lix'inu; Staph. (iuf( iis in the a,u;ar), 

 the me(,liuni was clarilied, the zones of 

 hacterial ly^sis being at times suri-ounded l)y 

 a halo of incomplete clarification. This 

 phenomenon was explained by assum- 

 ing \hv existence of a staphylococcal factor 

 fa\()rable to lysis by actinomycetes. This fac- 

 tor diffuses from the cells heated to 52 to 

 56°, or treated with an antiseptic, or dis- 

 solved through the action of actinomycetes. 

 Gratia and Dath (1925) also spoke of com- 

 plete lysis preceded by a preparatory stage 

 in which the microbes are agglutinated and 

 are swollen. 



Jones et al. have shown that certain acti- 

 nomycetes possess a system composed of a 

 lipoidal bactericidal substance, a ribonu- 

 clease, and a proteolytic enzyme. Killed 

 gram-negative bacteria as well as gram-nega- 

 ti\'e forms of gram-positive organisms are 

 lysed; living organisms are not affected. 

 Gram-positive bacteria are killed only under 

 conditions favorable to autolysis. 



The lysis of pathogenic bacteria by strep- 

 tomyces may be of considerable economic 

 importance. A culture producing a wine- 

 colored soluble pigment and a white to gray 

 aerial mycelium exerted a lysogenic effect 

 upon Fhytotnonas, Krwinia, and various 

 other gram-positive and gram-negative bac- 

 teria. I'otato extract-glucose agar media 

 were particularly fa\'orable to the production 

 of the lytic agent. When the streptomyces 

 cultur(> was added to soil infected with Phy- 

 tomonas tabaci, the plants were protected 

 against infections. This points to the poten- 

 tial impoi'tance of such lytic agents in soil 



|)rocesses and Iheir relation to true anti- 

 biotics (DarpouN .Mnd i'"ai\ re-Aniiot ). 



Paknla and lye used an act inoniycet in 

 l)reparation for the extraction of deoxyri- 

 lioniicleic acids from bacteria. 



l*r<Mlii<-| ion and Arli>ili<>s of A«'lino- 

 pliaj.M' 



\arious actinomycetes can he attacked by 

 lilterahle \iruses or phages, known as acti- 

 nophages. In this respect, the organisms show 

 a high degree of specificity. These actino- 

 phages occur abundantly in nature, particu- 

 larly in mamn-es and soils (Gilmour and 

 Butala). 



Wiebols and Wiei'inga were the first to ob- 

 sei'\e, in 19:^0, that cultures of certain acti- 

 nomycetes, now considered as species of 

 Streptomyces, isolated from infected potatoes 

 underwent lysis. This was found to be due 

 to the production of a specific, transmissible 

 phage. Repeated additions of phage-contain- 

 ing culture filtrates to fresh cultures of the 

 organism resulted in the development of a 

 phage which produced a large number of 

 plaques in cultures of the same organism 

 grouii on solid or in li(|uid media. Phages ac- 

 tive upon the animal pathogens .4. bewis and 

 .V. farcinica were also obtained. One culture 

 produced a polyvalent phage which was also 

 active upon *S. scabies. 



Miilhens (1941) made a study of the mech- 

 anism of phage action upon actinomycetes. 

 The whole colony was found to be attacked, 

 beginning at the periphery and proceeding to 

 the center. In some cases the culture had to 

 be repeatedly reinoculated into phage-con- 

 taining preparations before lysis was attained. 



The interest in the phages of actinomycetes 

 received a new stimulus with the discover}' 

 of the potentialities of some of these organ- 

 isms to produce important antibiotics. This 

 first became evident in the pioduction of 

 streptomycin by S. griseus. 



The sensitivity of streptomycin-jn-oducing 

 strains of S. f/nseus to different phages raised 



