Lactobacillus rhamnosus MP108: Toxicological evaluation

A lyophilized powder of Lactobacillus rhamnosus MP108, a strain isolated from infant feces, has been developed for potential as a probiotic. To assess safety, three genetic toxicity studies (Ames, in vivo mouse micronucleus, and in vivo mouse spermatocyte chromosome aberration assays) and one 90-day oral rat toxicity study were conducted. Lactobacillus rhamnosus MP108 had no activity in the Ames assay, with or without metabolic activation, up to the highest dose tested (5000 mu g/plate). Also, no evidence of genotoxicity was observed in the two in vivo genotoxicity assays up to the maximum dose tested of 5.6 g/kg body weight. Feeding of L. rhamnosus MP108 to SD rats at doses of 0, 0.25, 0.5, or 1.5 g/kg body weight/day had no statistically or biologically significant effects on any of the parameters measured. An evaluation of Lactobacillus spp. generally, and L. rhamnosus specifically, showed no indication of concern for translocation or pathogenicity. The results of the toxicology studies showed no indications for safety concerns. Practical Application Lactobacillus rhamnosus MP108 is a bacterium that shows potential as a probiotic. While this bacterium has been used in food and food production, a series of studies were conducted to provide further assurance that this particular strain of L. rhamnosus is safe.