Synergy between Dairy Peptides and Proteins

α s2-casein f(183-207) and lactoferricin [lactoferrin f(17-41)] are two potent 3 antibacterial peptides derived from bovine milk proteins. The aim of this work was to 4 evaluate if the antimicrobial activity of natural compounds employed in food 5 preservation such as nisin could be enhanced by combination with the aforementioned 6 milk peptides. Combinations with lactoferrin were also performed. Some of the 7 combinations used, such as lactoferrin with lactoferricin-B or lactoferrin with α s2-casein 8 f(183-207) may be relevant for the host defense properties of lactoferrin. This work 9 further highlights the potential of using nisin in combination with α s2-casein f(183-207) 10 to improve its effectiveness at inhibiting food-borne pathogens. ABSTRACT 26 Antimicrobial peptides derived from food proteins constitute a new field in the 27 combined use of antimicrobial agents in food. The best examples of milk-derived 28 peptides are those constituted by bovine lactoferricin [lactoferrin f(17-41)] (LFcin-B) 29 and bovine α s2-casein f(183-207). The aim of this work was to study if the antimicrobial 30 activity of a natural compound employed in food preservation, nisin, could be enhanced 31 by combination with the afore-mentioned milk-derived peptides. Furthermore, the 32 possibility of a synergistic effect between these peptides and bovine lactoferrin (LF) 33 against Escherichia coli and Staphylococcus epidermidis was also studied. Finally, the 34 most active combinations were assayed against the food-borne pathogens Listeria 35 monocytogenes and Salmonella choleraesuis. Results showed a synergistic effect when 36 LFcin-B was combined with bovine LF against E. coli. In the same way, the 37 combination of LFcin-B with bovine LF was synergistic against St. epidermidis. Bovine 38 LF and nisin increased their antimicrobial activity when they were assayed together 39 with bovine α s2-casein f(183-207). It is important to note the synergistic effect among 40 LFcin-B and bovine LF, as both compounds might be simultaneously in the suckling 41 gastrointestinal tract, and could, therefore, have a protective effect on it. The other 42 synergistic effect highlighted is that between α s2-casein f(183-207) and nisin against L. 43 monocytogenes because of the ability of L monocytogenes to develop resistance to nisin. 44 45