It is well known that alternative food additives are being researched following the prohibition of the addition of antibiotics to poultry feed as growth factors. Recently, antimicrobial peptides (AMPs) have been considered as alternatives to antibiotics. AMPs, produced by bacteria, insects, amphibians and mammals, as well as by chemical synthesis. In particular, their natural antimicrobial properties and their low tendency to create resistance in micro-organisms suggest that they might be a good alternative to antibiotics. They are not only effective against bacteria, but are also known to be effective against fungi and viruses. In studies on pigs and broiler chickens, they have been shown to be beneficial effects on growth performance, nutrient digestibility, the immune system, intestinal morphology and gut microbiota. Antimicrobial peptides are small biological molecules formed from 12-60 amino acids. AMPs have been reported to kill bacteria, in particular those showing resistance to multiple antibiotics. AMPs block the development of harmful bacteria while encouraging the growth of beneficial bacteria. For instance, it has been reported that sublancin reduces the Clostridium perfringens count while increasing the numbers of Lactobacilli. Furthermore, they have been proved to have a strong effect against Staphylococcus aureus and Pseudomonas aeruginosa. Some of the AMPs used in broiler chicken feeding are sublancin, secropin, magainin, nisin and defensin. These peptides can be used by adding them to feed or to drinking water. This review has attempted to find an answer to the question of whether AMPs added to the feed of broiler chickens can be an alternative to antibiotics by examining previous studies.

In this study, the effects of lactococcin BZ from Lactococcus lactis ssp. lactis BZ and enterocin KP from Enterococcus faecalis KP (1600 AU/mL) on the activities of three different yoghurt cultures (Y1 and Y2: CHR Hansen, Denmark; Y3: Sacco, Italy) were investigated. Lactic acid bacteria counts and pH values of the samples were determined during the incubation period (at 42°C for 24 h). It was found that lactococcin BZ had bactericidal effect against only one yoghurt culture whereas enterocin KP was effective against two yoghurt cultures. When lactococcin BZ and enterosin KP were used in combination (1:1), they showed bactericidal effect against two yoghurt cultures.

Fermentation is the oldest traditional method in order to protect against spoilage and pathogenic microorganisms. Thermal treatment, pH and water activity lowering and preservative addition other food preservation techniques that are commonly used. Although, as preservatives, many improved antibiotic and chemical agents have been gained, there are some other factors such as rapid resistance to antibiotics used in bacteria, in order to limit their use in food, to be found dimensions of threatening human health of the chemical protection and to cause allergic reactions. Recently, studies on bacteriocins that are produced by the safe bacteria, such as lactic acid bacteria, contain no toxic and adverse effects for human consumption have gained sudden intensity in accordance with the request against consumers in developing microbiologically safe and minimal processed food. There are some important effects using of bacteriocins accepted the new generation of antimicrobial agents as food preservatives such as extension of shelf life, reducing of the use of chemical preservatives and the economic loss caused degradation by microorganisms. Nisin, defined as GRAS (Generally Recognized as Safe) by FDA and named the E234 code 'Nisin-protective' or 'natural protective' located in the food additives list, first used in 1988 as a natural preservative by prohibiting of antibiotics using in food in the US. Nowadays in more than 50 countries, there have been more successful implementation of the nisin protected up the food from milk and dairy products to canned foods many food products