pediocins

Pediocins are a family of bacteriocins produced by lactic acid bacteria of the genus Pediococcus, notably Pediococcus pentosaceus and Pediococcus acidilactici. They are a subset of class IIa bacteriocins, consisting of small ribosomally synthesized, cationic peptides typically around 44 amino acids in length. Many pediocins share a conserved N-terminal sequence, including the YGNGV motif, and a C-terminal region believed to influence target specificity. They are usually produced as prepeptides containing an N-terminal leader sequence that is removed during maturation; maturation and export commonly involve dedicated proteases and an ABC-type transporter encoded in the bacteriocin gene cluster. The mature pediocin is released into the environment.

Mechanism and spectrum: Pediocins act primarily by binding to the mannose phosphotransferase system (Man-PTS) of susceptible Gram-positive bacteria, especially Listeria monocytogenes, to form pores in the cell membrane, leading to leakage of cytoplasmic contents and cell death. They have a relatively narrow spectrum, with strong activity against Listeria and related species; activity against non-Listeria Gram-positives varies. They are generally heat-stable and active across a moderate pH range, but are sensitive to proteolytic enzymes.

Applications and regulation: Due to their potent activity against Listeria and stability, pediocins are explored as natural biopreservatives in foods, including dairy, meat, and ready-to-eat products, either as purified preparations or via cocultures of Pediococcus strains. In some regulatory contexts, pediocins or pediocin-producing cultures are considered for food safety applications, subject to approval and safety assessment.