Pre-clinical safety and toxicity assessment of Limosilactobacillus fermentum NCDC 400 in murine model

Comprehensive safety assessment of potential probiotic strains is crucial in the selection of risk-free strains for clinical translation. This study aimed to evaluate the biosafety of Limosilactobacillus fermentum NCDC 400, a potential probiotic strain, using oral toxicity tests in a Swiss albino mouse model. Mice were orally gavaged with low (108 CFU/mouse/day) and high (1010 CFU/mouse/day) doses of NCDC 400 for 14 (acute), 28 (subacute), and 90 (subchronic) days to assess behavioral, hematological, biochemical, immunological, and histological effects. The administration of NCDC 400 did not result in any observable adverse effects on general health parameters, including body weight, feed and water intake, and organ indices. Hematological and biochemical parameters, such as glucose, serum enzymes, urea, creatinine, serum minerals, total serum proteins, and lipid profile, remained largely unaffected by the test strain. Notably, NCDC 400 administration led to a significant reduction in harmful intestinal enzymes and improvement in gut health indices, as indicated by fecal pH, lactate, ammonia, and short-chain fatty acids. There were no instances of bacterial translocation of NCDC 400 to blood or extra-intestinal organs. Immune homeostasis was not adversely affected by repeated exposure to NCDC 400 in all three oral toxicity studies. Histopathological examination revealed no strain-related changes in various tissues. Based on these findings, a dose of 1010 CFU/mouse/day was considered as the No Observable Effect Level (NOEL) in healthy mice. In conclusion, this study demonstrates the safe and non-toxic behavior of L. fermentum NCDC 400. The results support and ensure the safety and suitability for clinical trials and eventual translation into clinical practice as potential probiotic.