Safety studies of LP20 powder produced from heat-killed Lactobacillus plantarum L-137

The safety of LP20 and its prototype, a powder, with potential use in food, produced from a mixture of dextrin and heat-killed Lactobacillus plantarum L-137, was assessed in an acute study in mice, and in an in vitro bacterial reverse mutation assay, an in vitro chromosome aberration assay, and an in vivo mouse micronucleus assay. LP20 prototype was not acutely toxic when administered to male and female Slc:ICR mice by single gavage at 2000 mg/kg bw. Dosing was not associated with mortality, clinical signs, changes in bodyweight, or macroscopic abnormalities. The LD₅₀ in mice was greater than 2000 mg/kg bw. There was no evidence of genotoxicity of LP20 in the Ames assay (0–5000 μg/plate) or in the in vitro chromosome aberration assay with Chinese hamster lung fibroblasts (0–5000 μg/mL). Administration of two consecutive daily doses of 500, 1000, or 2000 mg/kg bw by gavage to male Crlj:CD-1 mice was not associated with an increased incidence of micronuclei and did not alter the ratio of polychromatic to normochromatic erythrocytes. These studies show that LP20 powder is not acutely toxic and is without genotoxic activity both in vitro and in vivo.