Isolation and antimicrobial potential of fermented dairy products' exopolysaccharide-producing lactic acid bacteria

Lactic acid bacteria possess significant industrial relevance due to their capacity to withstand harsh environmental conditions and metabolic capabilities. These microorganisms synthesize diverse metabolites that contribute to desirable technological and organoleptic properties to food products, particularly fermented dairy commodities. One specific metabolite of interest is exopolysaccharides (EPSs), which have gained attention due to their bioactive properties and various applications. EPSs are particularly important in the production of fermented products and ensuring the safety and quality of food due to their food preservation, product stability, and potential health-promoting properties

This study aimed to isolate and identify the lactic acid bacteria that produce EPSs from traditional Moroccan fermented dairy products, specifically Lben, Raib, Jben, and Klila. Subsequently, the lactic acid bacteria that produced EPSs were tested for their antimicrobial activity using the spot method against the following pathogenic bacteria: Listeria monocytogenes CECT 4032, Staphylococcus aureus CECT 976, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922.

Seven samples of different fermented dairy products were analyzed for EPS-producing strains. Forty-eight strains were considered to produce EPSs and twenty-seven strains among them were identified as lactic acid bacteria and exhibited inhibitory activity against different pathogenic bacteria. Their antimicrobial properties suggest their potential use as natural food preservatives.