Production of 10-hydroxydecanoic acid-enriched “fermented royal jelly” using Lactobacillus Panisapium M1 and verification of its safety and immunostimulating effect

Royal jelly (RJ) contains 10-hydroxydecanoic acid (10HDAA), which is expected to have immune activation effects, such as promoting M cell differentiation. To enhance the use of RJ as a functional immunostimulatory food ingredient, it is desirable to increase its 10HDAA content. Our aim was to isolate bacteria capable of converting 10-hydroxy-2-decenoic acid (10H2DA) contained in RJ to 10HDAA, thereby applying the isolate for producing fermented RJ with a high 10HDAA content. A strain of lactic acid bacteria, strain M1, was successfully isolated from the digestive tract of queen bees, capable of converting 10H2DA to 10HDAA. It was identified as Lactobacillus panisapium . By cultivating strain M1 in a protease-treated RJ broth, fermented RJ (fRJ) containing five times the amount of 10HDAA compared to conventional RJ was produced. Preliminary evaluations of fRJ’s immune-stimulating effects revealed several benefits. It promoted the differentiation of M cells, which play a crucial role in intestinal immunity, activated the phagocytic ability of macrophages, and increased IgA secretion in individuals with reduced salivary immunoglobulin (Ig) A secretion. Safety tests confirmed that fRJ is safe for consumption. fRJ acts on M cells, which tend to decrease with age, and promotes salivary IgA secretion. This suggests that fRJ could be a novel immune-stimulating food rich in active ingredients.