Exploring whole-genome analysis of a gamma-aminobutyric acid -producing marine Lactiplantibacillus plantarum: genomic insights into neuroactive and probiotic potential.

GABA-producing lactic acid bacteria are gaining attention as psychobiotics capable of influencing the microbiota-gut-brain axis, yet marine-derived strains remain poorly characterized. Here, the complete genomic characterization is reported for the marine strain Lactiplantibacillus plantarum EI6, focusing on its probiotic potential, GABA production, and safety. The 3.3 Mb genome (44.5% GC) encodes multiple probiotic-associated genes for acid/bile tolerance, adhesion, and stress response (including heat and cold-shock adaptation), antioxidant activity, and immunomodulation. Genome mining identified the glutamate decarboxylase system (gadB), and GABA production was experimentally confirmed by TLC and HPLC analysis, with a production level of 0.96 g/L. The genome also contains putative bacteriocin gene clusters (plantaricins and sactipeptides) and secondary metabolite BGCs (terpenes, RiPP-like, T3PKS). Safety analysis revealed no major virulence factors or antibiotic resistance genes, supporting a non-pathogenic profile. These findings position L. plantarum EI6 as a promising safe potential psychobiotic candidate for neuroactive and functional food applications.