Purification, Characterization and Mechanism Study of Enterocin ECHO-1: A Novel Bacteriocin Produced by <i>Enterococcus faecalis</i> WP2

A bacteriocin-producing strain isolated from Chinese pickles was identified as <i>Enterococcus faecalis</i> WP2. Through a four-stage purification process involving XAD-16 resin adsorption, cation-exchange chromatography, gel filtration, and RP-HPLC, a novel bacteriocin called Enterocin ECHO-1 was obtained from this strain. This antimicrobial peptide, with a low molecular mass of 1407.7 Da. Enterocin ECHO-1 demonstrated exceptional stability, retaining significant activity after autoclaving (121 °C) and under a wide range of pH conditions. Genomic analysis identified a dedicated biosynthetic gene cluster responsible for its production. The primary antibacterial mechanism has been identified as rapid and effective disruption of the cytoplasmic membrane: exposure to Enterocin ECHO-1 leads to immediate pore formation, complete dissipation of the proton motive force (PMF), collapse of transmembrane electrical (ΔΨ) and pH (ΔpH) gradients, depletion of intracellular ATP, and ultimately cell lysis. Enterocin ECHO-1 shows promise as a candidate for the development of natural biological preservatives or therapeutic agents.