G.M. Preciado, M.M. Michel, S.L. Villarreal-Morales, A.C. Flores-Gallegos, J. Aguirre-Joya,
J. Morlett-Chávez, C.N. Aguilar and R. Rodrıguez-Herrera

Food Research Department, School of Chemistry, Universidad Autonoma de Coahuila, Saltillo, Coahuila, Mexico

INTRODUCTION Bacteriocins are bioactive antimicrobial peptides (AMPs), also known as antimicrobial proteins, that are synthesized in the ribosome and extracellularly released. These compounds are produced by many bacteria and can kill or inhibit the growth of other bacteria. They show great potential against antibiotic-resistant strains.1 Bacteriocins are produced by both Gram-positive and Gram-negative bacteria. These compounds confer to bacteria a competitive advantage in their environmental niche to reducing competition for resources and form an important component of its chemical defense system.2 Bacteriocins were first identified in 1925. Production of these proteins is widespread among bacterial species, and it has been suggested that virtually all bacterial species could produce them.3 A great diversity of bacteriocins has been reported in most bacterial species, and there are cases where one bacterial species can produce different types of bacteriocins.4 The most studied bacteriocins are produced by lactic acid bacteria (LAB)5 because the use of these bacteria and their metabolic products is generally considered as safe (GRAS, Grade One).6,7 LAB are involved in fermentation and food preservation, and improvement of their hygienic quality by inhibiting the competitive flora, including pathogens,4 makes them ideal for use as bio-preservatives or microbial biocontrol.8 One concern about the use of bacteriocins as food preservatives is the possible appearance of natural or acquired bacteriocin resistance (BACR) by bacterial pathogens. Natural resistance to class IIa bacteriocins has been reported in 18% of the wild-type strains tested.

4 Chapter 2016