Antibiotics are produced by either bacteria or fungi. Actinomycetes produce two-thirds of the known antibiotics. Many of them are the third generations of certain classes of antibiotics, such as the β-lactam group. Unfortunately, many multidrug-resistant (MDR) microbes have recently been isolated from polluted foods. This showed that there is a need to find other innovative ways to inhibit MDR bacteria based on natural agents such as lactic acid bacteria (LAB), natural native and modified proteins, singly or in combination with antibiotics. The resistance mechanisms to antibiotics are due to genetic determinants, the thickening of the bacterial cell wall,
Certain reasons lead to resistance due to the ability of the bacterial pathogen to secrete enzymes that can degrade the antibiotic such as β-lactamases. Of the innovative natural agents which can inhibit bacterial pathogens are LAB; their metabolites inhibit the bacterial pathogens and their resistant variants such as organic acids, acetaldehydes, diacetyl, and bacteriocins.
Many genera of LAB, such as Lactobacillus, Lactococcus, and Enterococcus, produce bacteriocins or antimicrobial proteins of a broad spectrum of activity against bacterial pathogen. Therefore, bacteriocins have been used for food preservation and have been shown to extend the shelf life of foods. Natural legume proteins, either native or modified by methylation, showed a broad spectrum of antimicrobial activity as the positive charges of methylated proteins attach with negatively charged phospholipids of the cell membrane, making hydrophobic-hydrophobic interactions. This leads to the formation of pores in cell membranes, from which leakage of electrolytes occurs and causes cell death.