Evaluation of the safety and probiotic properties of GABA-producing Enterococcus faecium AB157 based on whole genome and phenotype analysis

Enterococcus faecium is a facultative anaerobic lactic acid bacterium that is a part of the human gut microbiota. This study reports the whole-genome sequence and comprehensive assessment of the safety and probiotic properties of a prominent γ-aminobutyric acid (GABA)-producing E. faecium AB157 strain isolated from Sichuan Paocai. The genome size of E. faecium AB157 was 2,490,719 bp, encoding 2273 genes, with an average guanine-cytosine (GC) content of 38.42%. The safety of E. faecium AB157 was confirmed by evaluating antibiotic resistance genes, virulence genes, and mobile genetic elements as well as by testing for hazardous metabolites and antibiotic sensitivity. The genome contains numerous stress response and adhesion related genes. In vitro experiments have confirmed favorable gastrointestinal fluid tolerance, adhesion ability, antioxidant and antibacterial activities. Furthermore, the GABA biosynthesis pathway of E. faecium AB157 was predicted based on the related metabolic genes. These results suggest that E. faecium AB157, which has excellent probiotic properties, is a potential probiotic candidate due to its ability to produce GABA. • Comprehensively assessed probiotics and safety of E. faecium AB157 based on genome and phenotype. • Analyzed the GABA biosynthesis pathway in E. faecium AB157. • The E. faecium AB157 has potential probiotic application.