DETERMINATION OF ANTAGONISTIC ACTIVITY OF YEAST IN MILK AND MILK-BASED PRODUCTS

Abstract

Yeasts are widely regarded by consumers as a safe and reliable source of ingredients and additives for food production. They also serve as an excellent model for studying natural barriers against harmful or spoilage-causing bacteria. This study aimed to identify native yeasts with antagonistic activity against food-relevant pathogenic bacteria and evaluate their potential both qualitatively and quantitatively. Ten yeast strains were isolated from fifteen milk and dairy product samples collected from various sources. Biofilm formation, a key indicator of antimicrobial potential, was assessed using the Congo red test, revealing that five out of ten isolates produced biofilms. These biofilm-forming yeasts were tested for antagonistic activity against Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus using the agar diffusion method.