There is a lack of efficient and safe preservatives in the food industry. Massive use of some common food preservation methods has led, over the years, to development of a resistance to different treatments by various food pathogens. Enteric bacteria are especially tolerant to adverse environmental conditions-such as low pH and high salt concentrations-which limits efficiency of some preservation methods. Consumers demand for natural, preservative-free, and minimally processed foods and worldwide concern regarding disease outbreaks caused by food-related pathogens have created a need for development of new classes of antimicrobial (AM) agents. The twentieth century revealed a massive array of new peptide-based antimicrobials. Small ribosomally made compounds are found in practically all living species where they act as important component of host defense. Certain indubitable advantages of peptides-pertaining to simplicity, activity spectra, and bacterial resistance-over known preservative agents advocate their potential for food preservation. Nisin, an AM compound originating from bacteria, is so far the only FDA-approved peptide. However, a growing number of reports describe the potential of animal-derived antimicrobial peptides as food preservatives. These studies have yielded various native compounds and/or derivatives that possess markedly improved antimicrobial properties under a broad range of incubation conditions. The present work reviews the most investigated peptides and accounts for their potential use as alternatives to the preservatives used today. The focus is on research aspects aiming at understanding the mechanism of action of these peptides at extreme environments of various food systems. Collectively, the data accumulated are convincingly indicative of potential applications of these peptides in food safety, namely, with respect to fighting multidrug-resistant pathogens.

Antibacterial properties of the frog-derived peptide dermaseptin S4 and a series of synthetic derivatives against the food pathogen Escherichia coli O157:H7 were investigated under extreme incubation conditions. The 28-mer analog K 4 K 20 S4 (P 28 ) displayed an MIC of 8 M and rapid bactericidal kinetics under standard culture conditions. Potent bactericidal properties were maintained at high salt concentrations, under acidic or basic conditions, and at extreme temperatures. The N-terminal 14-mer sequence (P 14 ) displayed higher potency (MIC, 4 M) but only within a narrow range of incubation conditions, pointing to the importance of the C-terminal domain of P 28 . The potency range was reextended upon conjugation of aminododecanoic acid to P 14 . The resulting lipopeptide was even more potent (MIC, 2 M) and affected bacterial viability under most of the conditions tested, including in commercial apple juice. The mechanistic implications of peptides' hydrophobicity, charge, structure, and binding to an idealized membrane were probed and are discussed here. Collectively, the data indicate interest in simple peptide-based compounds for design of antimicrobials that affect pathogens under a variable range of incubation conditions. Antimicrobial peptides (AMPs) are important components of innate immunity (23, 39, 52). Many are active towards a wide range of microorganisms by a mode of action which is still not fully understood but is assumed to involve interaction with the bacterial membrane and its disruption. AMPs do not require interaction with a chiral center for activity, supporting a lower probability for microorganisms to develop efficient resistance mechanisms compared with conventional antibiotics (22,38).AMPs from the dermaseptin family were recently proposed as model peptides for investigating the effects of acyl conjugation (13,17,44). These amphibian-derived AMPs (35, 36) have been amply investigated during the past decade and shown to exert rapid cytolytic activity against a wide range of microorganisms, including gram-negative and gram-positive bacteria, protozoa, filamentous fungi (14,26,35,36), spores of pathogenic bacteria (29), yeasts (11), and intracellular parasites (13,17,30), as well as antiviral activity (5).Due to its distinctive primary structure, dermaseptin S4 was used to identify structure-function relationships, which eventually led to potent derivatives (19,21,31,37,38). In recent work, we defined the activity of a single-amino-acid-substituted derivative, K 4 -S4, against Escherichia coli O157:H7 in terms of milieu dependencies (51). Extending that study, the present work is aimed at understanding the molecular elements in native dermaseptin S4 that are necessary for maintaining antimicrobial potency under extreme incubation conditions. We produced a set of derivatives that varied in length, composition, hydrophobicity, and net charge and investigated the effect of incubation conditions on the peptides' activity and bacterial susceptibility. In addition, we investigated the peptides' ...

Antimicrobial packaging is part of the broader area of active packaging, in which the package absorbs/releases different compounds during the product's storage and plays a major role in maintaining quality, extending shelf-life and improving the product's safety. Antimicrobial packages are capable of inhibiting the detrimental effects of spoiling microorganisms in food products. There has been very great interest in antimicrobial packaging in recent years and many such packaging materials have been proposed, some of which containing synthetic additives and others natural additives. In the present study, antimicrobial materials containing the antimicrobial peptide (AMP) dermaseptin K 4 K 20 -S4, which shows cytolytic activity in vitro against a broad spectrum of pathogenic microorganisms, such as bacteria, protozoa, yeast and filamentous fungi, were investigated. The study was aimed at evaluating the potency of this AMP as an antimicrobial agent for antimicrobial food packaging in two forms: (a) an aqueous solution of AMP was applied onto a polyethylene shrink-wrapping film; (b) the AMP was incorporated in a corn starch-based coating and applied directly onto the foodstuff (fresh cucumbers). Of these two versions, the latter has shown a greater efficiency against moulds and aerobic bacteria, even at lower surface concentrations of AMP (4.5 mg/dm 2 vs. 3.5-3.8 mg/dm 2 ) in the coating. While in the first version the AMP had slowed down the growth of microorganisms only slightly, incorporation of AMP into the coating caused a reduction in their concentration practically to zero.