title: Inhibitory effect of plantaricin peptides (Pln E/F and J/K) against Escherichia coli.
abstract: Plantaricins are small bioactive peptides produced by Lactobacillus plantarum strains that exhibit significant antimicrobial activity against closely-related Gram-positive bacteria, including food spoilage organisms. In comparison, bacteriocins including plantaricins, are usually less effective against Gram-negative organisms. In this study, we demonstrate that heterologously expressed and purified plantaricins, Pln E, -F, -J, and -K when tested against Gram negative model organism Escherichia coli K-12 were highly effective under certain conditions. The apparent tolerance of Gram-negative members to these peptides has been explained on the basis of the presence of the outer membrane (OM) that acts as a protective barrier. We have shown that agents and/or conditions that destabilize OM of E. coli K-12, make it susceptible to plantaricin peptides. In order to further strengthen this conclusion, an OM lipoprotein-defective lpp mutant strain of E. coli K-12 was also studied and compared. A significant loss of cell viability both in terms of CFU/ml as well as with live-dead dual staining combined with flow cytometry, could be demonstrated with the lpp mutant in comparison to the wild type strain. The results indicate that plantaricins can inhibit Gram-negative bacteria if the outer-membrane is weakened and it can be used in preservation of food with the help of some food-grade chelating agents.
authors.affiliation: Department of Genetics, University of Delhi South Campus, New Delhi, 110021, India.
authors.forename: Gargi
authors.initials: G
authors.lastname: Pal
authors.forename: Sheela
authors.initials: S
authors.lastname: Srivastava
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001430:Bacteriocins / Q000378:metabolism / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D015169:Colony Count, Microbial; D004361:Drug Tolerance; D048168:Escherichia coli K12 / Q000187:drug effects*; D048191:Lactiplantibacillus plantarum / Q000378:metabolism*; D050296:Microbial Viability / Q000187:drug effects*; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology*; D010539:Permeability
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D010455:Peptides