Glutamate in the medium of Lactiplantibacillus plantarum FL-664 affects the production of IL-12(p40) on murine spleen cells

Lactic acid bacteria (LAB) have been attracting attention for their effects on innate immunity, and therefore, it is required to develop an efficient culturing method while maintaining their functionality. In this study, first, we compared the growth and functionality of LAB cultured on food grade (FG) medium with those on standard LAB medium and found that LAB cultured in the FG medium were smaller in cell size with high yield and had a higher ability to induce IL-12(p40) production by murine spleen cells in vitro. Moreover, the higher the glutamate concentration in the medium, the smaller the cell size, and the higher the yield and the higher the ability to induce IL-12 production. Addition of glutamate to the culture medium changes the size of LAB and affects their ability to induce IL-12(p40) production. In conclusion, regulating the concentration of glutamate would be important in the efficient culturing of functional LAB.