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 degrees 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.