Enterocins of Enterococcus faecium, emerging natural food preservatives

Enterococci are distinct lactic acid bacteria, and also natural inhabitants of human and animal intestinal tracts. They may enter food products during processing through direct or indirect contamination and are mostly present in fermented food products, such as cheese, sausages, olives, etc. Nowadays, they are extensively studied for the production of bacteriocins (enterocins), which prevent the growth of many food-borne and spoilage-causing pathogens, such as Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Pseudomonas spp., Bacillus spp. and Clostridium spp. Enterocins belong to class I, class IIa, class IIc, and class III of bacteriocins. Enterocins can be used in different food products in order to enhance their shelf life because they are heat stable and show activity over wide pH range. Enterocins are effective as well as safe to be used in the food system because they are generally recognized as safe (GRAS). Enterococcus faecium and Enterococcus faecalis are the predominant bacteriocin-producing species of Enterococcus in food products. The following review is focused on the bacteriocin-producing strains of Enterococcus faecium isolated from different traditional fermented food products. The aim of this review is to cover general features of the enterocins of Enterococcus faecium, the attempts made to purify them, and their potential application in different food products to improve their overall safety.