Cytotoxicity in Vero cells and cytokines analyses in Balb/c mice as safety assessments of the probiotic mixtureSaccharomyces cerevisiaeRC016 andLactobacillus rhamnosusRC007 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)Saccharomyces cerevisiaeRC016 (Sc) andLactobacillus rhamnosusRC007 (Lr) for use as feed additive. Vero cells (10(4)cells per well) were exposed toSc(2 center dot 08 x 10(7), 2 center dot 08 x 10(6); 2 center dot 08 x 10(5)cells per ml),Lr(8 center dot 33 x 10(7); 8 center dot 33 x 10(6); 8 center dot 33 x 10(5)cells per ml) and their M (1 : 1).Scconcentrations did not affect the Vero cells viability; in contrast, they were lower when exposed toLr(P < 0 center dot 0001). Vero cells showed increasing viability with M decreasing concentrations (91% viability with M2). Control BALB/c mice received only phosphate buffer saline and the others received the M. The IL-10, IL-6 and TNF alpha concentrations from intestinal fluid were analysed and no significant differences were observed among treatments. The same occurred with the ratio between IL-10/TNF-alpha. 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.