Purification, Characterization and Antibacterial Mechanism of Bacteriocin from Lactobacillus Acidophilus XH1

Purpose: To carry out the extraction, purification and biological characterization, and assess the antibacterial activity of bacteriocin from Lactobacillus acidophilus XH1. Methods: Chloroform extraction method was used for bacteriocin extraction while characterization of bacteriocin was carried out by flat-dug well agar diffusion assay. The antibacterial mechanisms of bacteriocin were examined by scanning electron microscopy and atomic emission spectroscopy. The molecular weight of lactobacillin XH1 was measured using Tricine SDS PAGE electrophoresis. Results: The bacteriocin (lactobacillin XH1) inhibited Escherichia coli, Staphylococcus aureus and Bacillus anthracis. It showed a wide range of antimicrobial activity at pH 1.0 5.0 while at 37 – 120 °C, it was sensitive to trypsin, pepsin and papain, but insensitive to proteinase K and neutral protease. The intracellular UV-absorbing substances,, namely, lactate dehydrogenase macromolecules, K and ATP of E. coli, decreased rapidly. The molecular weight of lactobacillin XH1 was approximately 16 kDa. Conclusion: Lactobacillin XH1 is a broad-spectrum antimicrobial substance that is thermostable. Its antibacterial mechanism on Escherichia coli is similar to that of bacteriocins on Gram-positive bacteria. The agent is a hydrophobic protein with more acidic groups.