Cytotoxicity in Vero cells and cytokines analyses in Balb/c mice as safety assessments of the probiotic mixture Saccharomyces cerevisiae RC016 and Lactobacillus rhamnosus RC007 for use as a feed additive

The objective was to carry out cytotoxicity assays in Vero cells and cytokines analyses in Balb/c mice as safety assessments to evaluate the probiotic mixture (M) S. cerevisiae RC016 (Sc) and L. rhamnosus RC007 (Lr) for use as feed additive. Vero cells (104 cells well-1 ) were exposed to Sc (2.08 x 107 , 2.08 x 106 ; 2.08 x 105 cells mL-1 ), Lr (8.33 x 107 ; 8.33 x 106 ; 8.33 x 105 cells mL-1 ) and their M (1:1). Sc concentrations did not affect the Vero cells viability; in contrast, they were lower when exposed to Lr (P ˂0.0001). Vero cells showed increasing viability with M decreasing concentrations (91% viability with M2). Control BALB/c mice received only PBS and the others received the M. The IL-10, IL-6 and TNFα concentrations from intestinal fluid were analyzed and no significant differences were observed among treatments. The same occurred with the ratio between IL-10/TNF-α. Beneficial effects of probiotics are associated with the regulation of the excessive inflammatory response; it is desirable they can modulate the cytokines production only under pathological conditions. Here, M administration to healthy mice did not induce negative side effects and expands the knowledge about beneficial effects of using probiotic microorganisms in mixture for feed additives development.