Abstract
Lactic acid bacteria (LAB) are pivotal in food preservation and exhibit immunomodulatory effects on interleukin-10 (IL-10) and interleukin-12 (IL-12) production. Lactiplantibacillus plantarum (L. plantarum) and Lactiplantibacillus pentosus (L. pentosus) from fermented food are known for their effect; however, a comprehensive comparative genome analysis is needed to identify the linked genes. Here, we investigated the immunomodulatory capability at the genome level of L. plantarum and L. pentosus strains isolated from Japanese pickles at the genome level, and we further identified their immunomodulation-associated genes using the potential-gene (PG) index derived from the Calinski-Harabasz (CH) index. The results revealed an immunostimulatory clade with strain-specific IL-10 and IL-12 induction and identified key genes via the PG index. Both genes across two species were shown to encode the enzyme TagF2, which is crucial for synthesizing poly-glycerol-3-phosphate type wall teichoic acid (poly-GroP WTA), indicating that TagF2 plays a potential role as an effective microbe-associated-molecular-pattern. In vivo analyses confirmed the IL-10-inducing ability of one strain, reinforcing the IL-10-stimulating capacity of its poly-GroP WTA. Subpotential genes in L. plantarum TagF2-possessing strains were linked to host‒cell interactions, suggesting that such strains play potential probiotic roles. Collectively, the PG index effectively identified immunomodulation-related genes, thus paving the way for the use of the PG index to detect potential health benefit-associated genes in other LAB species. IMPORTANCE: Lactic acid bacteria are pivotal in food preservation and exhibit immunomodulatory effects on interleukin-10 (IL-10) and interleukin-12 (IL-12) production. Lactiplantibacillus plantarum and Lactiplantibacillus pentosus from fermented food are known for such effect, yet comprehensive comparative genome analysis is needed to elucidate the linked genes of the two species. The significance of our research is in observing the immunostimulatory clade with strain-specific cytokine induction and identifying key immunostimulation-related genes encoding enzymes that are crucial for synthesizing a potentially effective microbe-associated-molecular-pattern using the potential-gene index across two species. The further in vivo validation reinforced the interleukin-10-stimulating capacity of the identified pattern, and the detected sub-potential genes in Lactiplantibacillus plantarum key-gene possessing strains implied the utility of potential-gene index in detecting potential health-benefit-associated genes in other lactic acid bacteria species.