Bo Som Lee, O-Hyun Ban, Won Yeong Bang, Seung A Chae, Sangki Oh, Chanmi Park, Minjee Lee, Soo-Jung Kim, Jungwoo Yang and Young Hoon Jung. Safety assessment of Lactobacillus reuteri IDCC 3701 based on phenotypic and genomic analysis. Annals of Microbiology. 71(10) : 1 - 6 (2021)

Purpose: Lactobacillus reuteri is one of the most largely studied human-commensal bacteria and widely used as a form of probiotics. Safety of probiotics has become increasingly important for human consumption due to increasing health-concerns in food industry. In this study, the safety of L. reuteri IDCC 3701 isolated from human breast milk was thoroughly investigated.

Methods: Whole-genome sequence analysis was performed to identify antibiotic resistance and toxigenicity of L. reuteri IDCC 3701. Phenotypic analysis such as minimal inhibitory concentration, β-hemolysis, extracellular enzyme activity, and the production of biological amines and L/D-lactate, was investigated. Finally, acute oral toxicity test

was performed to access L. reuteri IDCC 3701 safety.

Results: Although multiple resistances to gentamicin and kanamycin were observed in L. reuteri IDCC 3701, it was revealed that these resistances are intrinsic and not transferable through whole-genome analysis. In addition, various phenotypic analysis concerning hemolysis, enzyme activity, and D-lactate production did not show any negative results. Although L. reuteri IDCC 3701 harbors a histidine decarboxylase gene, no biogenic amines were detected. Finally, L. reuteri IDCC 3701 exhibited no evidence of acute toxicity according to an in vivo study.

Conclusion: Our findings demonstrate that L. reuteri IDCC 3701 is considered to be safe for human consumption as probiotics based on the in silico, in vitro and in vivo studies.