Lactiplantibacillus plantarum LRCC5314 includes a gene for serotonin biosynthesis via the tryptophan metabolic pathway

As the functions of probiotics within the same species may not be shared, it is important to analyze the genetic characteristics of strains to determine their safety and usefulness before industrial applications. Hence the present study was undertaken to determine functional genes, and beneficial activities of strain LRCC5314, a bacterial strain isolated from kimchi through comparative genomic analysis. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain LRCC5314 was a member of the species L. plantarum. Whole genome size of strain LRCC5314 was sequence was 3.25 Mb long, with a G + C content of 44.5 mol% and 3,031 predicted genes. Strain LRCC5314 could metabolize hexoses through homofermentation, which produces only lactic acid from hexoses. According to gene annotation, strain LRCC-5314 contained genes of EPS production and CRISPR. Moreover, the strain contained genes that could encode a complete biosynthetic pathway for the production of tryptophan, which can be used as a precursor of serotonin. Notably, the tryptophan and serotonin activities strain LRCC5314 were higher than those of reference strains, L. plantarum ATCC 14917^T, DSM 20246, DSM 2601, and ATCC 8014, which reach tryptophan amount of 0.784 ± 0.045 μM/ml in MRS broth and serotonin concentration of 19.075 ± 0.295 ng/ml in HT-22 cells. These findings indicated that L. plantarum LRCC5314 could provide a source for serotonin production and could be used as a functional probiotic for stress regulation.