In silico, in vitro and in vivo safety assessment of three Limosilactobacillus mucosae strains for probiotic candidates

Previous studies indicated that Limosilactobacillus mucosae had a good ability to regulate lipid metabolism, however, there was limited research on its safety. In this study, we assessed the safety of three L. mucosae strains including genotypes and phenotype, subacute oral toxicity test, and their influences on immunosuppressed mice. The results showed that there were no virulence genes or genetic islands with clear pathogenicity in the genomes of L. mucosae DCC1HL5, FZJTZ26M3, and GD16M9. All three strains were resistant to chloramphenicol, additionally, DCC1HL5 was resistant to kanamycin and tetracycline, but the possibility of horizontal transfer of their resistance genes was relatively low. L. mucosae DCC1HL5, FZJTZ26M3, and GD16M9 did not produce biogenic amine, and alpha-hemolysis was found. The results of the 28-day subacute oral toxicity test showed that 109 CFU of each strain did not cause significant abnormalities in various aspects such as body weight, organ indexes, histopathology, hematological parameters, fasting blood glucose, serum lipids, liver parameters, and intestinal inflammation in both healthy and immunosuppressed mice. Therefore, L. mucosae DCC1HL5, FZJTZ26M3, and GD16M9 have the potential for safe application in functional foods.