title: Mechanism underlying prolongevity induced by bifidobacteria in Caenorhabditis elegans.
abstract: Lactobacilli and bifidobacteria are probiotic bacteria that modify host defense systems and have the ability to extend the lifespan of the nematode Caenorhabditis elegans. Here, we attempted to elucidate the mechanism by which bifidobacteria prolong the lifespan of C. elegans. When the nematode was fed Bifidobacterium infantis (BI) mixed at various ratios with the standard food bacterium Escherichia coli strain OP50 (OP), the mean lifespan of worms was extended in a dose-dependent manner. Worms fed BI displayed higher locomotion and produced more offspring than control worms. The growth curves of nematodes were similar regardless of the amount of BI mixed with OP, suggesting that BI did not induce prolongevity effects through caloric restriction. Notably, feeding worms the cell wall fraction of BI alone was sufficient to promote prolongevity. The accumulation of protein carbonyls and lipofuscin, a biochemical marker of aging, was also lower in worms fed BI; however, the worms displayed similar susceptibility to heat, hydrogen peroxide, and paraquat, an inducer of free radicals, as the control worms. As a result of BI feeding, loss-of-function mutants of daf-16, jnk-1, aak-2, tol-1, and tir-1 exhibited a longer lifespan than OP-fed control worms, but BI failed to extend the lifespan of pmk-1, skn-1, and vhp-1 mutants. As skn-1 induces phase 2 detoxification enzymes, our findings suggest that cell wall components of bifidobacteria increase the average lifespan of C. elegans via activation of skn-1, regulated by the p38 MAPK pathway, but not by general activation of the host defense system via DAF-16.
authors.affiliation: Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Komura
authors.forename: Takanori
authors.initials: T
authors.lastname: Ikeda
authors.forename: Chikako
authors.initials: C
authors.lastname: Yasui
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saeki
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Nishikawa
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D001644:Bifidobacterium / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000235:genetics / Q000382:microbiology* / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D031204:Caloric Restriction; D004032:Diet; D004926:Escherichia coli / Q000502:physiology; D017238:Genes, Helminth; D008062:Lipofuscin / Q000378:metabolism; D008136:Longevity / Q000502:physiology*; D009154:Mutation; D050050:Protein Carbonylation; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D008062:Lipofuscin; D048051:p38 Mitogen-Activated Protein Kinases