The inhibitory effects of pyrocarbonic acid diethyl ester on lactobacillus casei and its phage Jl – A novel strategy for phage control in technical fermentation processes^†

The effects of pyrccarbonic acid diethyl ester (PADE) on Lactobacillus casei Sl and its phage Jl was investigated in relation to the control of phages in the dairy industry and other technica fermentation processes.

PADE exhibited a bacteriostatic effect at 0.5 to 8 mM and a bactericidal effect at 10 mM or higher. It inhibited the growth of the phage at its bacteriostatic and bactericidal concentrations. The growth inhibition of the phage was reversible at the bacteriostatic concentrations but complete and irreversible at the bactericidal concentrations. PADE inactivated the free phage within several minutes; 10 and 30 mM of PADE inactivated 90 and 100%, respectively, of the phage. It completely decomposed into ineffective components in several minutes. The bacteria grew almost normally when they were inoculated after the complete decomposition of PADE.

These four characteristics of PADE – its bactericidal effect, its inhibitory effect on phage growth, its phage-inactivating effect and its decomposition – suggest a novel strategy for phage control in technical fermentation processes, including the dairy industry.