Impacts of Bacillus subtilis var. natto on the lifespan and stress resistance of Caenorhabditis elegans

Bacillus subtilis var. natto is used in the production of natto, a typical Japanese fermented soybean food. Although the probiotic attributes and health-related effects of B. subtilis var. natto have been reported, the effect on longevity remains unknown. In the present study, the effects of B. subtilis var. natto strains on lifespan extension and the molecular mechanisms governing the prolongevity were examined using Caenorhabditis elegans as a model animal.Synchronized 3-day-old (young adult) worms were fed Escherichia coli OP50 (control) or a subcloned isolate of B. subtilis var. natto Miyagino strain (MI-OMU01) and subjected to lifespan, survival against pathogens and abiotic stress resistance assays. Notably, the lifespan of worms fed MI-OMU01 was significantly longer than that of the animals fed OP50. Moreover, MI-OMU01 increased the resistance of C. elegans to several stressors, including UV irradiation, H2O2, and Cu2+.Genetic and gene expression analyses using mutant animals suggested that MI-OMU01 extended the lifespan of worms in TIR-1/SARM, p38 MAPK, and insulin/IGF-1 signaling pathway-dependent manners.