Potential Applications of the Cyclic Peptide Enterocin AS-48 in the Preservation of Vegetable Foods and Beverages

Abstract

Bacteriocins are antimicrobial peptides produced by bacteria. Among them, the enterococcal bacteriocin (enterocin) AS-48 stands for its peculiar characteristics and broad-spectrum antimicrobial activity. AS-48 belongs to the class of circular bacteriocins and has been studied in depth in several aspects: peptide structure, genetic determinants, and mode of action. Recently, a wealth of knowledge has accumulated on the antibacterial activity of this bacteriocin against foodborne pathogenic and spoilage bacteria in food systems, especially in vegetable foods and drinks. This work provides a general overview on the results from tests carried out with AS-48 in different vegetable food categories (such as fruit juices, ciders, sport and energy drinks, fresh fruits and vegetables, pre-cooked ready to eat foods, canned vegetables, and bakery products). Depending on the food substrate, the bacteriocin has been tested alone or as part of hurdle technology, in combination with physico-chemical treatments (such as mild heat treatments or high-intensity pulsed electric fields) and other antimicrobial substances (such as essential oils, phenolic compounds, and chemical preservatives). Since the work carried out on bacteriocins in preservation of vegetable foods and drinks is much more limited compared to meat and dairy products, the results reported for AS-48 may open new possibilities in the field of bacteriocin applications.

Natural Antimicrobials for Biopreservation of Sprouts

“…When using live microbial antagonists as protective cultures in food biopreservation, there is a number of limitations and rules that need to be taken into consideration (Galvez et al, 2007): i) the protective cultures must not be pathogenic or produce toxins against humans or animals, and must not modify the organoleptic properties of the food product; ii) they must be able to multiply in the food and produce antagonistic activity at the food storage temperature; ii) they must be efficient in controlling the bacterial pathogen of concern under the common food storage and processing conditions. There has been a great interest in the application of bacteriocins and bacteriocin-producing strains (especially those produced by the LAB) on the preservation of foods of animal origin, but to a much less extent on vegetable foods such as sprouted seeds (Gálvez et al, 2008;Abriouel et al, 2010). Cai et al (1997) isolated a collection of bacteria from mung-and soy bean-sprouts from retail stores and tested them for anti-listerial activity.…”

“…Enterocin AS-48 is a broad-spectrum cyclic antimicrobial peptide produced by E. faecalis and E. faecium strains (reviewed by Maqueda et al, 2004). This bacteriocin has been widely investigated in food systems against foodborne pathogenic bacteria such as L. monocytogenes, S. aureus, B. cereus, E. coli or S. enterica (Abriouel et al, 2010;Ananou et al, 2005;Cobo Molinos et al, 2005Grande et al, 2006Grande et al, , 2007aMartínez Viedma et al, 2008Muñoz et al, 2007). Partially-purified preparations of enterocin AS-48 can be produced easy on semi-synthetic media (Abriouel et al, 2003) and on whey-based substrates (Ananou et al, 2010), which makes this bacteriocin an amenable antimicrobial for application in foods.…”

AS-48 bacteriocin: close to perfection

“…Its antimicrobial activity against food-borne Grampositive and Gram-negative pathogenic (E. coli, Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus) and food-spoilage bacteria (Bacillus spp., Paenibacillus spp.) has been extensively documented [15,23,24]. These characteristics, together with its stability and solubility over wide pH and temperature ranges, confer a clear potential to be used as food biopreservative.…”

“…These characteristics, together with its stability and solubility over wide pH and temperature ranges, confer a clear potential to be used as food biopreservative. In fact, this bacteriocin has been successfully employed against different pathogens in a broad array of products, including salads, desserts, milk, cheeses, fruit juices, vegetables sauces, acid-fermented sausages, rice-based foods, soybean sprouts, canned food, and coconut milk (reviewed by [23] and [24]). Besides this, AS-48 could also have a veterinary application, since liposome-encapsulated AS-48 inhibits the growth of a S. aureus strain isolated from mastitis in dairy cows [25].…”

Bactericidal effects of high hydrostatic pressure treatment singly or in combination with natural antimicrobials on Staphylococcus aureus in rice pudding

“…Nisin is widely used as a licensed food preservative (Thomas, Clarkson, & Delves-Broughton, 2000). Enterocin AS-48 is a cyclic antimicrobial peptide that has been tested singly and on combination with other hurdles such as food preservatives or pulsed electric fields for inactivation of bacteria in foods (Abriouel, Lucas, Ben Omar, Valdivia, & Gálvez, 2010;Maqueda et al, 2004). Given the increasing number of reports on the incidence of MRSA in food production animals (such as mastitis in dairy cows) as well as in foods (Argudín et al, 2012;Vanderhaeghen, Hermans, Haesebrouck, & Butaye, 2010), the present study was designed to evaluate the effects of HHP treatment on inactivation of a cocktail of MRSA strains by HHP in rice pudding as a model dairy food, singly or in combination with natural antimicrobials (nisin, enterocin AS-48, clove oil and cinnamon oil).…”