Abstract
Diethyl pyrocarbonate (DEPC) inhibited the intracellular growth of Lactobacillus casei phage J1. At bacteriostatic concentrations of DEPC (0.5-8mM) growth inhibition of the phage was reversible; after the decomposition of DEPC into ineffective components the phage burst began to occur with a prolonged latent period. At bactericidal concentrations of DEPC (10mM or greater) growth inhibition of the phage was completed and irreversible; the number of infective center rapidly decreased and, thereafter, did not increase.
DEPC (10mM) blocked the lysis of phage-infected cells. Artificial lysis of the lysis-inhibited cells revealed no intracellular mature phage particles. DEPC blocked an early stage(s) of phage growth, resulting in an inhibition of the synthesis of phage structural proteins, including antigenic materials having serum-blocking power, and phage DNA. However, DEPC seemed not to react with the injected phage DNA. The addition of DEPC at any time during the latent period also produced an immediate inhibition of the syntheses of phage protein and phage DNA and the cellular lysis, even after these had been initiated. The results are discussed in relation to the control of phage infection in dairy fermentation.
