54 BACTERIOPHAGES 



lowed first-order kinetics to 99 per cent inactivation and then 

 slowed. With 2.8 per cent HgCl2 a phage stock titering 5 X 

 10^ per ml. could be completely inactivated in a few days. 

 Treatment of such a stock with hydrogen sulfide followed by 

 centrifugation resulted in complete reactivation. Essentially 

 similar results were obtained by Wahl (1939, 1946c) with six 

 different phages, which differed, however, in rate of inactivation. 

 Oxidizing agents such as peroxide, halogens, ozone, and 

 permanganate rapidly inactivate viruses. In contrast mild re- 

 ducing agents have no harmful effect and Wahl and Blum- 

 Emerique (1946) have suggested the addition of hydrosulfite to 

 protect phage preparations from oxidation during storage. 

 Contrary to general expectation, however, Alper (1954) sug- 

 gests that phage SI 3 is inactivated by the reducing action of 

 hydrogen peroxide. In support of this he finds that the in- 

 activation by peroxide is accelerated by exclusion of oxygen, 

 that mild oxidizing agents like chlorate and iodate do not in- 

 activate the phage, and that ascorbic acid does. The question 

 calls for systematic work. 



8. Sonic Vibration 



High intensity sonic vibrations imparted to a fluid medium by 

 a vibrating crystal or diaphragm can denature proteins and 

 destroy bacteria. They have been used to liberate enzymes 

 from bacteria by rupture of the bacterial cell walls (Shropshire, 

 1947). The effect of intense sonic vibration on the seven coli- 

 phages of the T group and on their common host, strain B of 

 E. coll, was studied by T. F. Anderson, Boggs, and Winters 

 (1948) using the Raytheon magneto-striction apparatus oper- 

 ating at about 9,000 cycles per second. The inactivation fol- 

 lowed the kinetics of a first order reaction and there was a large 

 variation in sensitivity among the phage strains tested. The 

 small particle phages Tl, T3, and T7 were relatively resistant 

 (99 per cent inactivation in 60 minutes) whereas the large 

 particle phages T2, T4, T5, and T6 were sensitive (99 per cent 

 inactivation in about 5 minutes). The host bacteria were 



