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Many fermented foods are known to have beneficial effects on human and animal health, offering anti-aging and immunomodulatory benefits to host. Microorganisms contained in the fermented foods are known to provide metabolic products possibly improving host health. However, despite of a number of studies on the functional effects of the fermented foods, isolation and identification of the effective bacterial strains in the products are still in progress. The objective of this study was to isolate candidate functional strains in various Korean traditional fermented foods, including ganjang, gochujang, doenjang, and jeotgal, and evaluate their beneficial effects on the host, using <i>Caenorhabditis elegans</i> as a surrogate animal model. Among the 30 strains isolated, five <i>Bacillus</i> spp. were selected that increased the expression level of <i>pmk-1</i>, an innate immune gene of <i>C. elegans</i>. These strains extended the nematode lifespan and showed intestinal adhesion to the host. Based on the bioinformatic analyses of whole genome sequences and pangenomes, the five strains of <i>Bacillus subtilis</i> were genetically different from the strains found in East Asian countries and previously reported strains isolated from Korean fermented foods. Our findings suggest that the newly isolated <i>B. subtilis</i> strains can be a good candidate for probiotic with further in-depth investigation on health benefits and safety.