Electron microscopy of Streptococcus lactis phage plaque margins.

Ultrathin sections of plaques produced by Streptococcus lactis phages O712 and m13 were examined by transmission electron microscopy. The clear central area of the plaque was found to contain hardly any cellular material but the turbid margin contained abundant plasma membranes and some partially lysed cells whose appearance suggests a novel mechanism for the termination of plaque growth.