Effect of Mitomycin C on Lactobacillus Casei-Phage J1 System

Abstract

The inhibition of intracellular growth of phage J1 by mitomycin C (40 μg/ml) was described. Mitomycin C failed to affect the infectivity of free phage, the adsorption of phage and the injection of phage DNA. But, the injected DNA irreversibly lost its infectivity. Mitomycin C inhibited the formation of phage DNA, of phage protein having serum-blocking power and of phage endolysin. Pulse treatment with mitomycin C and radiobiological analysis showed that an early stage of phage growth was blocked. Consequently, a primary and major action of mitomycin C on phage growth seems to be the formation of cross-links in the injected parental phage DNA which prevents the replication of phage DNA. When exposed to mitomycin C (0.3~1 μg/ml), L. casei S-1continued to grow for about 350 min and then began to lyse. Electron microscopic observation showed the presence of phage particles in the lysate and the infectivity of the particle was also proved. These results show that L. casei S-1 is lysogenic and phage development in the lysogenic strain is induced by mitomycin C. © 1972, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.