Abstract
The specific inhibition of bacteriophage by bacillary extracts recently described by us 1 , 2 and confirmed by Kligler and Olitski, 3 Burnet, 4 and Gough and Burnet 5 may be employed to study the chemical properties of these complex cellular products with the aid of various manipulations such as fractionation and hydrolysis.
In a previous communication, 2 the observation was made that crude saline extracts of B. aertrycke boiled in N/2 alkali, still retained their phage inhibiting capacity and, consequently, it seemed desirable to study in detail the sensitivity of these substances to alkaline and acid treatment before attempting purification. For this purpose, a crude saline extract of B. aertrycke was employed and tested for phage inhibition before and after boiling in N/2 sodium hydroxide for 5 minutes∗ and subsequent neutralization. Such alkali treated extracts showed marked increase in phage inhibiting capacity although they gave a precipitin titre that was slightly lower than that of the untreated material. This observation, therefore, indicated that the degree of inhibition of phage did not run parallel to the precipitin titre of the crude extract. Striking confirmation of this view was found when these extracts were subjected to mild hydrolysis in N/15 and N/30 hydrochloric acid at 80° C. This procedure was adopted because boiling for 5 minutes or longer in N/2 acid completely destroyed both the phage inhibiting reaction and also the capacity to react with precipitins.
A crude extract of B. aertrycke was dissolved in saline, passed through a Seitz filter and then treated with N/5 hydrochloric acid in sufficient quantity to produce a final concentration of N/15 acid and held at 80°C. Samples were removed at various intervals, neutralized, brought to a dilution of 1:500, centrifuged to remove the precipitates, and sterilized by heating for one hour at 80° C.
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