Editorial Article

Antimicrobials in food and the role of Bacteriocins

Dr. Giorgia Caruso
Contract Researcher, Istituto Zooprofilattico Sperimentale, Palermo, Italy
*Corresponding author:

Dr. Giorgia Caruso, Contract Researcher, Istituto Zooprofilattico Sperimentale, Palermo, Italy, Email: giorgia.cars@gmail.com

At present, the food business is compelled to tackle different challenges with relation to food safety, consumers’ demands, and new regulatory norms on the international level. In particular, the consumers’ awareness for natural healthy products has increased, but at the same time food industry has to face risks deriving from microbial contaminations.

The toxic effect of many chemical additives has become more popular, hence research has recently been impelled to find an adequate solution. Antimicrobial packaging with natural substances and natural biodegradable polymer films is a very promising improvement, satisfying the sustainability requirement of consumers. The application of bacteriocins has allowed to overcome this disadvantage, thus it has aroused interest in the food system since bacteriocins have been provided the GRAS (Generally Regarded As Safe) status, and can be used as bio- preservatives (Cotter et al 2005). Bacteriocins are produced by the majority of groups of bacteria. Specifically, lactic acid bacteria (LAB) are present in numerous food products and have always been widely utilized in the production of fermented products, so they are considered safe for human consumption (Ameen & Caruso 2017). Bacteriocins are ribosomally synthesized antimicrobial proteins which may have evolved for space and resource competition with other bacteria in the environment. In fact, they possess an antibacterial activity consisting in various mechanisms that alter the cell membrane permeability properties, as cytoplasmic membrane pore formation and cell wall interference. These peculiar bacteriocins show a notable thermal resistance; in addition, they can operate in a wide pH range. Furthermore, for their proteinaceous nature they can be degraded by proteolytic enzymes. As a result, target microorganisms have reduced possibilities of developing antibiotic resistance in these conditions (Cotter et al 2013). Numerous bacteriocins have been tested for their application as food preservatives and some are already commercially available, like nisin, a bacteriocin of Lactobacillus lactis, lactocin produced by strain of L. curvatus and pediocin PA-1/AcH, a bacteriocin of Pedicococcus acidilactici (Tong et al 2014). They can be added in concentrated preparations, or they can be produced in situ by LAB starter cultures. It has been shown that the combination of bacteriocins with hurdle technology treatments potentiates the antimicrobial activity. Usage of non-thermal treatments, for instance Pulsed Electric Field (PEF), together with bacteriocins, has proved beneficial in controlling pathogens (Sobrino-Lopez & Martin Belloso 2006). Recently, bioactive packaging has emerged as another application of bacteriocins. Bioactive packaging can be used either incorporating bacteriocins directly into polymers or into packaging films through coating or adsorbing bacteriocins to the surface of polymers, as biodegradable protein films (Appendini & Hotchkiss 2002). The latter process may be achieved by heat press or adsorption of bacteriocin on certain polymeric materials (Zacharof & Lovitt 2012). In various types of meat, bacteriocins from L. curvatus immobilized in polyethylene film reduced the microbial counts of L. monocytogenes during shelf life storage (Ercolini et al 2006); according to Okuda et al (2013), the potent antibiotic vancomycin was found to be less effective on MRSA (methicillin-resistant Staphylococcus aureus) planktonic and biofilm cells, in respect to some bacteriocins (i.e. nisin A and lacticin Q), which had a stronger bactericidal activity. Polyvinyl alcohol films carrying nisin inactivated L. monocytogenes for 90-day storage in fermented sausages (Marcos et al 2013). Nisin coating embedded in a cellophane-based packaging decreased total aerobic bacteria counts in chopped meat for more than 10 days at refrigeration temperature (Guerra et al 2005). Antimicrobial packaging provides additional efficiency over cell fermentation in situ (increased productivity, longer stability and greater process control) and also over the direct incorporation of bacteriocin in the food product. In fact, for instance the immobilization technique in packaging allows a slower release of the antimicrobial compound in food and the protection of the antimicrobial activity when exposed to proteolysis (Bali et al 2014; Le-Tien et al 2004). Immobilization may be carried out by different methods: adsorption, which is characterized by low reproducibility, as is based on reversible weak forces, as hydrophobic interactions and van der Walls forces (Guisan 2006), ionic binding in which the molecule is charged, resulting in a more electrostatically stable complex, entrapment, which involves inclusion of bacteriocins within the pore system of the matrix and microencapsulation in a semi-permeable membrane characterized by a controlled porosity. However, the efficiency of bacteriocin and its release depend on the physico-chemical characteristics of the food matrix. Temperature, water activity and pH are crucial factors, hence different levels of microbial inhibition may be observed by using different food products (Coma 2008; Katla et al 2002). For instance release of bacteriocin from the film is affected by a higher temperature, and also food pH may influence the characteristics of bacteriocins by ionization (Mauriello et al 2005). Nisin has a higher solubility at lower pH, resulting in more diffusion from packaging material.

Lately the use of bacteriocins has also shifted, including a diverse array of applications, extending even to the biomedical field (Shin et al 2016). Different studies have reported the potential of nisin and its bioengineered variants against foodborne and nonfood-related pathogens (Field et al 2012), and also in human diseases (Balciunas et al 2013).

In conclusion, it is then extremely important to continue studying and exploring the varied field of bacteriocins, for widening our reserve of antimicrobial compounds for a better control of food and clinical pathogens. Therefore more research is needed, concerning toxicological aspects and safety evaluations of new bacteriocin molecules.

1. Ameen S, Caruso G (2017) Lactic Acid and Lactic Acid Bacteria. Current Use and Perspectives in the Food and Beverage Industry. Lactic Acid in the Food Industry. SpringerBriefs in Chemistry of Foods, in press
2. Appendini P, Hotchkiss JH (2002) Review of antimicrobial food packaging. Innov Food Sci and Emerg Technol 3:113–126
3. Balciunas EM, Martinez FAC, Todorov SD, de Melo Franco BDG, Converti A, de Souza Oliveira RP (2013) Novel biotechnological applications of bacteriocins: a review. Food Cont 32:134–142
4. Bali V, Panesar PS, Bera MB (2014) Potential of immobilization technology in bacteriocin production and antimicrobial packaging: A Review. Food Rev Int DOI:10.1080/87559129.2014.924138
5. Coma V (2008) Bioactive packaging technologies for extended shelf life of meat-based products. Meat Sci 78(1):90-103
6. Cotter PD, Hill C, Ross RP (2005) Bacteriocins: developing innate immunity for food. Nat Rev Microbiol 3:777–788
7. Cotter PD, Ross RP, Hill C (2013) Bacteriocins - a viable alternative to antibiotics? Nat Rev Microbiol 11:95–105
8. Ercolini D, Storia A, Villani F, Mauriello G (2006) Effect of a bacteriocins activated polythene film on Listeria monocytogenes as evaluated by viable staining and epifluorescence microscopy. J Appl Microbiol 100:765–772
9. Field D, Begley M, O'Connor PM, Daly KM, Hugenholtz F, Cotter PD, Hill C, Ross RP (2012) Bioengineered nisin A derivatives with enhanced activity against both Gram-positive and Gram-negative pathogens. PLoS ONE 7:e46884
10. Guerra NP, Macias CL, Agrasar AT, Castro LP (2005) Development of a bioactive packaging cellopane using Nisapln as biopreservative agent. Lett Appl Microbiol 40(2):106-110
11. Guisan JM (2006) Immobilization of enzymes and cells. In: Methods in Biotechnology, 2nd ed. (Walker JM Ed.); Humana Press: Totowa, USA. Vol 22 pp. 15-30
12. Katla T, Moretro T, Sveen I, Aasen IM, Axelsson L, Rorvik LM, Naterstad K (2002) Inhibition of Listeria monocytogenes in chicken cold cuts by addition of sakacin P and sakacin P‐producing Lactobacillus sakei. J Appl Microbiol 93(2):191-196
13. Le-Tien C, Millette M, Lacroix M, Mateescu MA (2004) Modified alginate matrices for the immobilization of bioactive agents. Biotechnol Appl Biochem 39(2):189-198
14. Marcos B, Aymerich T, Garriga M, Arnau J (2013) Active packaging containing nisin and high pressure processing as post processing listericidal treatment for convenience fermented sausages. Food Cont 30:325-330
15. Mauriello G, De Luca E, La Storia A, Villani F, Ercolini D (2005) Antimicrobial activity of a nisin-activated plastic film for food packaging. Lett Appl Microbiol 41:464-469
16. Okuda K, Zendo T, Sugimoto S, Iwase T, Tajima A, Yamada S, Sonomoto K, Mizunoe Y (2013) Effects of bacteriocins on methicillin-resistant Staphylococcus aureus biofilm. Antimicrob Agents Chemother 57:5572-5579
17. Shin JM, Gwak JW, Kamarajan P, Fenno JC, Rickard AH, Kapila YL (2016) Biomedical applications of nisin. J Appl Microbiol 120:1449–1465
18. Sobrino-Lopez A, Martin Belloso O (2006) Enhancing inactivation of Staphylococcus aureus in skim milk by combining high-intensity pulsed electric fields and nisin. J Food Prot 69:345–353
19. Tong Z, Zhang Y, Ling J, Ma J, Huang L, Zhang L (2014) An in vitro study on the effects of nisin on the antibacterial activities of 18 antibiotics against Enterococcus faecalis. PLoS ONE 9:e99513
20. Zacharof MP, Lovitt RW (2012) Bacteriocins produced by lactic acid bacteria: a review article. APCBEE Procedia 2:50-56

Published: 26 June 2017

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© 2017 Caruso. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.