Probiotic is defined as “a live microbial feed supplement which beneficially affects the host animal by improving its intestinal microbial balance”. The mechanisms through which probiotics exert their health benefits include antimutagenic properties, stimulation of host defence systems, immunomodulation and the competitive exclusion of pathogens by production of small, cationic antimicrobial peptides (AMPs). Defensins are small cationic antimicrobial peptides predominantly found in leukocytes and epithelial cells engaged in host defense. This work study the relation between probiotic... Probiotics also defined as “live micro-organisms, that when included in foods can influence the composition and the activity of the gut microbiota, modulate the inflammatory response, improve the nonspecific intestinal barrier, and reinforce or modulate the mucosal and the systemic immune response.’’ . The fermentation of dairy foods presents one of the oldest methods of long-term food preservation.