Effects of enterocin E1A on the ultrastructure of Streptococcus faecium

Streptococcus faecium 158 cells were examined by electron microscopy at sequential intervals after addition of enterocin E1A, a bacteriocin produced by Streptococcus faecium E1. After addition of enterocin E1A, the nuclear material began to concentrate into distinct areas at the center of the bacteria. In a later stage, extensive condensation of the nuclear filaments left a small cluster of dense granules within a cytoplasmic vacuole, and 10-20% of the cells underwent a complete lysis.