**1. Introduction**

*Staphylococcus aureus* is a spherical, nonsporulating, nonmotile bacterium, facultative aero-anaerobic, Gram-positive, and catalase positive. It belongs to the normal microbiota and is found on the skin and mucous of mammals and birds. This bacterium can be disseminated in the environment of its hosts and survives for long periods in these areas [1].

The determination of *S. aureus* in food products is done in order to establish its potential to cause food poisoning and demonstrate contamination after being processed. This microorganism produces enterotoxins formed in foods under broad conditions of pH, water activity, and redox potential [2].

On the other hand, the use of some of the genera of lactic acid bacteria (LAB), such as *Lactobacillus, Leuconostoc, Lactococcus*, as alternatives in the biopreservation of foods is due to their ability to produce secondary metabolites such as bacteriocins, organic acids, hydrogen peroxide, among others. Several researchers highlight species of the genus *Lactobacillus* as the main antagonists of pathogenic microorganisms and food microbial spoilers. It has been observed that some

species of *Lactobacillus* produce a variety of antimicrobial compounds that differ in their inhibitory spectrum, mode of action, structure and biochemical properties. *Lactobacillus plantarum* has an antagonistic effect on Gram-positive organisms and, in some cases, on Gram-negative organisms, such as *Listeria monocytogenes, Staphylococcus aureus, Streptococcus, Salmonella*, and *Pseudomonas* [3].

The objective of this work was to evaluate the stability of the antimicrobial activity of *Lactobacillus plantarum* NRRL B-4496 supernatants against *Staphylococcus aureus* ATCC 29413 during 20 weeks of storage at 25 ± 1.0°C.
