Abstract:To evaluate the safety and health risks of Lactobacillus kefiranofaciens subsp.kefiranofaciens ZW3，the present study carried out the toxicological evaluation of ZW3 by systematic in vitro and in vivo toxicological tests，including acute oral toxicity test on SD rats，bacterial reverse mutation（Ames）test，micronucleus assay in mice，and in vitro chromosomal aberration assay.The acute oral toxicity test showed that the LD50of ZW3 was greater than 10.0 g/kg BW.The results of the Ames test showed that ZW3 had no mutagenic properties to the five tested strains.In the micronucleus assay of mouse bone marrow cells，ZW3 did not cause an increase in the micronuclei-containing rate of mammalian polychromatic erythrocytes.The results of the chromosomal aberration assay in vitro showed that chromosomal abnormal cells and chromosome aberration rates in ZW3 groups with different doses were not significantly different from those in the negative control group.According to the comprehensive evaluation，L.kefiranofaciens subsp.kefiranofaciens ZW3 was at the actual non-toxic level，without genetic toxicity，mutagenicity，and carcinogenicity.