Multi-Model Longevity Assays Reveal Lifespan- and Healthspan-Promoting Effects of Bacillus subtilis WTC019

<i>Bacillus subtilis</i> is a spore-forming probiotic with an established safety profile, yet its effects on aging-related phenotypes remain incompletely defined. Here, we assessed the lifespan- and healthspan-promoting activity of a novel strain, <i>B. subtilis</i> WTC019, using integrated invertebrate, cellular, and mammalian aging models. In <i>Caenorhabditis elegans</i>, <i>B. subtilis</i> WTC019 significantly extended lifespan, increasing median lifespan by 17.48%, 90% lifespan by 35.36%, and maximum lifespan by 19.07%, and attenuated age-associated locomotor decline. In human skin fibroblasts, <i>B. subtilis</i> WTC019 cell lysate reduced senescence-associated β-galactosidase activity by approximately 34% and altered cell cycle distribution consistent with delayed cellular senescence. Moreover, dietary supplementation with <i>B. subtilis</i> WTC019 significantly prolonged lifespan in C57BL/6J mice, with median lifespan increases of 5.97% in females and 6.05% in males. Together, these results demonstrate that <i>B. subtilis</i> WTC019 promotes lifespan- and healthspan-associated phenotypes across multiple aging models, supporting its potential as a probiotic candidate for healthy aging interventions.