Lactic acid bacteria (LAB) produce a variety of low molecular mass compounds including acids, alcohols, carbon dioxide, diacetyl, hydrogen peroxide and other metabolites. Many of these metabolites have a broad activity spectrum against other species, and their production is largely affected by the food matrix itself. Bacteriocins inhibit only closely related species or other Gram-positive microorganisms. Several recent reports have described the synergistic effects between various antimicrobials, thus widening their application potential. New insights with respect to the effective control of Gram-negative bacteria using potential antibacterial agents should be realized by investigating possible mechanisms that either disrupt or bypass the permeability barrier function of the outer membrane.