Inhibition of Phage Growth by an Antibiotic Rugulosin Isolated from Myrothecium verucaria

The mechanism of anti-phage action of (—)rugulosin was investigated mainly using phage MS2. In the presence of the antibiotic, phage adsorption was not inhibited and phage–bacterium complexes did not remain in an antiserum-sensitive state. However, phage–bacterium complexes temporarily remained in a shear-sensitive state during the time immediately following phage infection and phage RNA penetrating into the host bacteria was decreased. The antibiotic also acted on preformed antiserum- and shear-resistant infective centers and inhibited the in vitro RNA synthesis by Qβ replicase. These results indicate that the mechanim of action of the antibiotic consists of at least 2 parts, i.e., the inhibition of the penetration of phage RNA into the host bacteria and some early intracellular reaction(s) for phage multiplication.