We are frequently reminded of the urgent need for a safer food supply by large-scale foodborne disease outbreaks and the frequency of massive food recalls. This was chillingly illustrated by the impact of the deadly enterohemorrhagic (EHEC) E. coli O104:H4 German outbreak in 2011 that resulted in more than 50 deaths, numerous serious illnesses, and tremendous economic damage to the European produce industry. EHEC E. coli and its cousin Salmonella are two of the most frequent causes of food recalls in the United States, illustrating that measures for controlling just these two Gram negative enterobacteria are woefully inadequate. There clearly is an urgent need for more antimicrobials that can be utilized to impart increased security to our food supply system against a broader range of potential foodborne pathogens. These, of course, need to be antimicrobials that are safe and “natural” as there is an equal consumer concern over the use of chemical preservatives in foods. Given the passage of the Food Safety Modernization Act (FSMA) in 2011, which requires the implementation of preventative measures against foodborne pathogens, this likely will be an essential component of the implementation of this law.
Antimicrobial Peptides. Natural antimicrobial peptides from food-grade sources provide an excellent opportunity to supply this increased safety assurance to the food supply system. There are no adverse consumer concerns about incorporating natural peptides in foods that are digested upon ingestion but have the increased functionality of antimicrobial activity while in the food system. Bacteriocins are peptide-based antimicrobials produced by many bacteria to inhibit competing bacteria in their habitat. This is just one of many “competitive” features that bacteria can use to inhabit different environments.
While many bacteriocins have a very small spectrum of antimicrobial activity, often limited to closely related species or even to just different strains within the same species, some do have a broad range. This particularly applies to the lantibiotics, which are a subclass of bacteriocins that undergo post-translation modifications, such as dehydration and cyclization reactions and, in some cases, the addition of groups to specific amino acids, thus forming novel amino acid structures (Willey and van der Donk, 2007). The effect of these modifications can greatly influence the stability of the peptide, thus making it more resilient to food processing conditions, as well as the antimicrobial spectrum.