Bacteriocins of Lactic Acid Bacteria as Potent Antimicrobial Peptides against Food Pathogens

Abstract

An ever-growing demand for food products with minimal chemical additives has generated a necessity for exploring new alternatives for food preservation. In this context, more recently, bacteriocins, the peptides having antimicrobial property, synthesized ribosomally by numerous bacteria have been attracting a lot of attention. They are known to possess the potential to restrict the growth of microorganisms causing food spoilage without causing any harm to the bacteria themselves owing to the presence of self-defensive proteins. In particular, the bacteriocins of lactic acid bacteria have been considered harmless and safe for consumption and are indicated to evade the development of unwanted bacteria. Use of bacteriocins as biopreservatives has been studied in various food industries, and they have been established to elevate the shelf life of minimally processed food items by exerting killing mechanism. They restrict the growth of undesirable bacteria by breaking the target cell membrane and finally resulting into pore formation. The current article provides an insight on bacteriocins of lactic acid bacteria, their biosynthesis, mechanism of action, and promising applications of these antimicrobial peptides in the food sector.

Biologically Active Compounds from Probiotic Microorganisms and Plant Extracts Used as Biopreservatives

“…For example, the mechanism of action of the class I bacteriocin nisin involves initial binding to lipid II in the cell wall, allowing the molecules to make contact with the membrane and form pores (Figure 1) [10]. Nisin is more effective against bacteria in the stationary phase of growth, while some bacteriocins, such as pediocin, can act independently of the membrane potential difference, affecting both the stationary and exponential growth phases [10]. Some bacteriocins demonstrate bactericidal effects towards related species and strains [13][14][15].…”

“…They can have α -helix, β -sheet, or both structures and may contain thioether linkages, disulfide bridges, or free thiol groups. The presence of an α-helical structure with opposite polar and nonpolar sides along the long chain enables bacteriocins to interact with both aqueous and lipid phases [ 10 ]. The complete amino acid sequences of many bacteriocins are not yet fully elucidated.…”

“…The bactericidal activity of bacteriocins is not necessarily correlated with the number of amino acids in their structure [ 10 , 11 ]. Bacteriocins can be classified into four main classes based on their properties, post-translational modifications, and the number of peptides in their mature molecule: Class I: lantibiotics; Class II: small, heat-stable peptides; Class III: high-molecular-weight, heat-labile peptides; Class IV: complex bacteriocins, including non-protein components such as lipids or carbohydrates [ 11 , 12 ].…”

“…Bacteriocins produced by lactic acid bacteria exhibit strong antimicrobial activity against various pathogens. Gram-positive bacteria are generally more sensitive to bacteriocins, while Gram-negative bacteria are usually resistant [ 10 ]. However, Gram-negative bacteria can become sensitive to bacteriocins under physical or chemical stress, which alters the structure of their cell-surface lipopolysaccharides.…”

“…However, Gram-negative bacteria can become sensitive to bacteriocins under physical or chemical stress, which alters the structure of their cell-surface lipopolysaccharides. The bactericidal effect against susceptible bacterial cells is achieved by destabilizing the cytoplasmic membrane [ 10 ]. Initially, bacteriocin molecules adsorb to the membrane surface and form temporary pores, resulting in the loss of the proton-motive force and pH gradient across the membrane [ 10 ].…”