Safety evaluation of Limosilactobacillus fermentum PS150 for use as a commercial psychobiotic

The psychobiotic Limosilactobacillus fermentum PS150 (PS150), isolated from fermented meat sausage, has antidepressant, anxiolytic, and sleep-improving properties. This study investigated the safety of PS150 using a genome-based safety evaluation, antibiotic resistance profiles, mutagenicity, clastogenicity, 28-day subacute toxicity, and gastrointestinal tolerance. Bioinformatics analysis indicated that PS150 did not carry genes encoding antimicrobial resistance, virulence factors, or enzymes related to biogenic amine production. Additionally, PS150 was sensitive to the eight antibiotics tested. Ames test results showed no signs of increased reverse mutations following PS150 treatment. Further, PS150 treatment did not increase the frequency of chromosomal aberrations or number of micronuclei, and administration of PS150 (1.3 × 10¹¹ CFU/kg, 2.6 × 10¹¹ CFU/kg and 4.3 × 10¹¹ CFU/kg) for 28 days did not cause any toxicity or mortality in mice. PS150 exhibited superior gastrointestinal tolerance both in vitro and in vivo, enabling it to endure and survive the digestive processes. In conclusion, our results suggest that L. fermentum PS150 is safe in mice, supporting its potential as a psychobiotic candidate for human use. The 28-day "No Observed Adverse Effect Level (NOAEL)" is defined at the highest dose of 4.3 × 10¹¹ CFU/kg body weight/day for the PS150 powder under the test conditions employed.