Purification and antimicrobial mechanism of a novel bacteriocin produced by Lactobacillus rhamnosus 1.0320

Abstract

For a long time, the abuse of antibiotics and the excessive use of synthetic preservatives have caused harm to human health. Bacteriocins produced by lactic acid bacteria (LAB) are nontoxic and exhibit potential as natural preservatives. In this experiment, the bacteriocin 1.0320 produced by Lactobacillus rhamnosus 1.0320 screened from traditional koumiss was used as the research object. The main purpose of the experiment was to purify bacteriocin 1.0320 and study its antimicrobial mechanism. Bacteriocin 1.0320 exhibited antimicrobial activity against gram-positive and gram-negative bacteria. Bacteriocin 1.0320 in cell-free fermentation supernatant (CFS) was purified by ethyl acetate extraction and anion exchange chromatography. The molecular mass of bacteriocin 1.0320 was 1–3.3 KDa as assessed by dialysis and Tricine sodium dodecyl sulphate-polyacrylamide gel electrophoresis (Tricine-SDS-PAGE). The minimum inhibitory concentration of bacteriocin 1.0320 on Escherichiacoli UB1005 was 0.072 mg/mL. Bacteriocin 1.0320 can form pores on the surface of cell membrane, increase the permeability of cell membrane, dissipate the cytoplasmic membrane potential and transmembrane pH gradient, and destroy the integrity of cell membrane, causing cell content to flow out and cell death. The effect is related to the concentration of bacteriocin 1.0320. This information provides the theoretical basis for the antimicrobial mechanism of L. rhamnosus bacteriocin.