AimsTo identify lactic acid bacterial isolates, which promote immunoglobulin A (IgA) production in honeybee products and honeybees (Apis mellifera). Methods and ResultsPyrosequencing analysis of the microbiota of honeybee products and honeybees revealed the predominance of Lactobacillus kunkeei in honey, bee pollen, bee bread and royal jelly. Lactobacillus kunkeei was isolated from bee pollen, bee bread and honey stomach, and its effect on IgA production was evaluated invitro. Heat-killed YB38 and YB83 isolates from bee pollen promoted IgA production in mouse Peyer's Patch cells and had little mitogenic activity or effect on IL-2 production in mouse spleen cells in comparison with Listeria monocytogenes, which does exhibit mitogen activity. A pilot study in 11 healthy adults showed that 4-week intake of 1000mgday(-1) heat-killed YB38 increased secretory IgA (SIgA) concentrations and secretion in saliva with no adverse effects. ConclusionHeat-killed Lact.kunkeei YB38 from bee pollen increases IgA production and may safely improve immune responsiveness. Significance and Impact of the StudyThis is the first report of microbiota analysis of royal jelly and the immune efficacy of Lact.kunkeei from honeybee products in humans.