I'HODrCTlON OK WTIHIOTICS 



241 



tialit ics. ( )| her ;iiit i])i(>tt)/,();iii nut ihiol ics pi'o- 

 iIucihI hy act iiioniycrlcs include coiiiiiocidiii, 

 ciifocidiii, t'ci'iuicidiii, and \ alinoniNcin. 



A niiinhcr of antixiral sutistanccs nrv also 

 ))r(Hlucc(l l)y actinoinycctcs. Sonic of tluMii, 

 like the tctnicyelines, are actix'c upon the 

 lafiicr \iruses, such as psittacosis, and ha\-e 

 already found extensive practical apjilica- 

 tion. Others are active^ ujion th(> smaller vi- 

 ruses l)ut are either insullicienl ly active or 

 are loo toxic to lia\e found practical applica- 

 tion. Anion<i these, it is sufficient to mention 

 ehrlichin, abikoviromycin, achroviromycin, 

 noformicin, hygrosporin, and i)rimycin. 



A number of actinom^Tetes arc also able 

 to produce antiphage agents (Jones and 

 Schatz). Some of these substances have been 

 gi\-en names hke chr^'somycin. 



Miscellaneous Antibiotics 



A hu'ge number of other antibiotics pro- 

 duced by actinomycetes, chiefly streptomy- 

 ces, ha\-e been described. Some have a wide 

 spectrum. Others have a narrower spectrum. 

 Still others have a verj^ narrow spectrum. A 

 few have found practical apphcations or of- 

 fer ])r()mise. 



Screening programs for antibiotics are be- 

 ing continued on a large scale. Particular at- 

 tention is being directed at present to agents 

 active against viruses and tumors. Although 

 a number of active substances have already 

 been isolated, none has so far given very 

 promising practical results in the treatment 

 of disease. 



It is important to note that various antibi- 

 otics of actinomycetes are also active against 

 plant pathogenic bacteria and fungi (Waks- 

 man et al, 1944). 



The great majority of antibiotics are pro- 

 duced by members of the genus Streptomyces. 

 A few are formed by species of Nccardia and 

 ^ficromonospora. Some of the thermophilic 

 actinomycetes have been found to possess an- 

 tibiotic properties (Kosmacherj. None of the 

 remaining genera (Actinoplanes, etc.) were 



'l\\ltl,K (17 



Release nf (uitihiotic aclivilij from mycelium of S. 



griscMi.s bti chemical and physical treatments 



(Perhnan and Langlykke) 



'rre;Umi-nt of my< clium suspension* 



Antibiotic 

 potency 

 released by 

 treatment, 

 Mg/ml 



None 19 



Heated in lioilint;- water l);tlli lor 10 luiii- 38 



iites 



Exposure to sonic eiiei't^y for 15 minutes 107 

 Addition of sufficient concentrated HCl 

 to give: 



1)H 5.1 .37 



pH 4.2 67 



1)H 3.0 109 



pH 2.5 188 



pH 1.8 175 

 Addition of sufficient 10 A' NaOH to give: 



pH 8.0 45 



pH 9.1 109 



pH 9.9' 161 



pH 10.8 143 

 Addition of sodium chloride to give con- 

 centration: 



0.003 M 19 



0.01 M 19 



0.03 M 33 



0.1 M 53 



0.3 iM 97 

 Addition of sodium sulfate to give con- 

 centration: 



0.003 M 19 



0.01 M 43 



0.03 M 97 



0.1 M 159 



0.3 M 147 

 Addition of sodium citrate to give con- 

 centration: 



0.003 M 25 



0.01 M 64 



0.03 M 142 



0.1 M 129 



0.3 M 130 



* Samples from 4-day-old fermentation were 

 centrifuged and the supernatant liquid assaj-ed. 

 The supernatant liquid contained 108 Mg/mf of 

 streptomycin. The collected solids were resus- 

 pended in distilled water to original volume, and 

 acid, alkali, or salt was added as indicated to 10-ml 

 aliquots. After 15 minutes of shaking on a mechan- 

 ical shaker the solids were collected by centrifuga- 

 tion and the supernatant liquid submitted for 

 ass a J'. 



