An Endeavor to Adapt a Trypsin Susceptible Bacteriophage to the Action of Trypsin.

Abstract

It is well known to students of the d'Herelle phenomenon that bacteriophages, with rare exceptions, resist the action of trypsin for indefinite periods of time. Recently, one of us 1 described the trypsin susceptibility of 2 races of staphylococcus bacteriophages; one a monovalent, the other a polyvalent race. These 2 races were found to be highly susceptible to the action of trypsin, complete inactivation following an exposure to this enzyme within 48 hours at incubator temperature. In view of the difference of opinion entertained by various investigators on the question of whether bacteriophages actually possess powers of adaptation, a property indicative of life, it occurred to us that this susceptibility to tryptic activity might possibly serve as a basis for determining further the capacity of bacteriophages to adapt themselves to deleterious or inhibiting agents.

Two methods of arriving at an answer were employed. In one series of experiments, the bacteriophage was exposed to the action of trypsin in the presence of lysable staphylococci. That is, the customary procedure for producing bacteriophage suspensions was employed, with the exception that the Martin's broth contained active trypsin.∗ After complete lysis had been attained the limpid liquid was filtered through a Chamberland candle (L 3). A few drops of the filtrate were then added to a fresh suspension of staphylococci in trypsinized broth and so on in series. Any adaptation that might be effected could be due either to an adjustment on the part of the bacteriophage, or, should the bacteriophage in reality represent a product of the bacteria themselves, to an adjustment on the part of the staphylococci producing it.