Antimicrobial Bacteriocins

Nisin is an antimicrobial bacteriocin (Section 6.6.3) produced by some strains of Lactococcus lactis subsp. lactis (Hurst and Hoover, 1993). The site of primary action is the bacterial membrane where the antibiotic disrupts cytoplasmic membranes (Hurst and Hoover, 1993). 

In the field of muscle foods, the use of marination before irradiation reduced the dose necessary to eliminate Salmonella in poultry [113]. Some antimicrobial additives, especially the natural ones (e.g., bacteriocins) [94] and GRAS (generally recognized as safe) preservatives [114] can be usefully combined with irradiation to reduce dose requirements. Some antioxidants have also been used to prevent the undesirable oxidative effects in irradiated foods. 

Lantibiotics. Certain antimicrobial peptides have been identified which contain "unusual" amino acids such as lanthionine, /3-methyllanthionine, dehydroalanine, and jS-methyldehydroalanine. Due to the predominance of lanthionine they have been collectively referred to as "lantibiotics" (26). Among the lactic acid bacteria, two bacteriocins have been identified as lantibiotics, nisin and lacticin 481. Nisin, the first... 

From the data presented in Figure 3, it is likely that heat-stable LAB bacteriocins (other than nisin) may find suitable application as biologically-produced antimicrobials ("biopreservatives") in thermally-processed foods. Future studies directed towards the examination of a variety of novel bacteriocins in thermal processing applications may identify new LAB bacteriocin(s) which have comparable, or perhaps superior, properties as nisin. Further research is needed to determine the presence of bacteriocins in retail foods which may help to reduce the regulatory hesitancy towards their practical application as safe food ingredients. Data provided by research with the magainins and... 

Antimicrobial peptides, relation to food quality-CortrirtMe / heat stability among lactic acid bacteria bacteriocins, 315-318 inhibitory activity, 308-309 interaction with food components, 314-315... 

Bacteria, use of antimicrobial proteins for control, 6 Bacteriocins Escherichia colU 304 lactic acid bacteria, 304-307t Barrier concept, use of antimicrobial peptides, 303... 

Most antimicrobial peptides produced by Gram-positive bacteria are classified as bacteriocins, and like microcins they are diverse in size and structure.35 36 Recent classification schemes divide bacteriocins into three classes lantibiotics (class I), heat-stable non-lantibiotics (class II) and heat-labile antimicrobial proteins (class III), of which the majority of bacteriocins belong either to class I or class II. NMR spectroscopy has been applied in numerous studies of bacteriocins and an overview of the range of diversity in the 3D structures that have been determined by NMR spectroscopy is provided in Figure 4. 

Bacteriocins are antimicrobial peptides ribosomally synthesized in bacteria. These are classified into four or five classes.136 Class II bacteriocins are heat-stable nonlantibiotic peptides. Unlike lantibiotics described in the next section, class II bacteriocins are less modified disulfide bridge and some N-terminal modifications are known in some class II bacteriocins. It is well known that the biosynthesis of some of the class II bacteriocins is regulated by quorum sensing mediated by inducer peptide pheromones.95,137-1... 

Montville, T.J. and Bruno, M.E.C. 1994. Evidence that dissipation of proton motive force is a common mechanism of action for bacteriocins and other antimicrobial proteins. Int. J. Food... 

De Vuyst, L. and Vandamme, E.J. 1994. Antimicrobial potential of lactic acid bacteria. In Bacteriocins of Lactic Acid Bacteria (L. De Vuyst and EJ. Vandamme, eds), pp. 91-142. Blackie Academic and Professional, Glasgow. 

Leuconostoc Starter culture in dairy fermentation Antimicrobial activity by producing various bacteriocins... 

Organic acids (lactic, acetic) Bacteriocins co2 Hydrogen peroxide Diacetyl Reuterin Ethanol Increase acidity, antimicrobial compounds Nisin only bacteriocin permitted as food preservative, disrupts cytoplasmic membrane Reduces membrane permeability Oxidizes proteins Interacts with arginine-binding proteins Not confirmed, may interact with thiol group in proteins that may lead to oxidative stress (Whitehead et al., 2008)... 

A culture cocktail has been developed, consisting of a lactic acid producing bacterial culture condensate mixture (LCCM) to be applied as an antimicrobial. This mixture has a low pH and also contains bacteriocin-like... 

In synthetic polymers, as well as edible films, various classes of antimicrobial compounds have been evaluated. These include organic acids, enzymes, bacteriocins, and other compounds which may consist of tri-closans, silver zeolites, and fungicides. Several approaches are followed when incorporating an antimicrobial substance into packaging material (Quintavalla and Vicini, 2002) ... 

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