In mammals, the beneficial bacteria residing in the host intestine (that is, gut or commensal flora) play a crucial role in immune system development, tissue morphogenesis and aging. Beneficial effects of the gut flora on host physiology, including slowing of aging, might be improved with the incorporation of probiotic bacteria into the host diet.
Probiotics are live organisms that have a beneficial effect on host health when they are administered or present in adequate quantities. However, the mechanisms causing potential prolongevity effects of beneficial bacteria on different hosts remain poorly understood.
Microbial biofilms are three-dimensional structured communities of adherent microorganisms encased in a self-produced extracellular matrix, containing networks of channels for nutrient supply and long-distance cell-to-cell communication. Bacteria living in biofilms are physiological very distinct from their planktonic counterparts, and they function as a cooperative consortium more similar to that of multicellular organisms than a unicellular organism. The crucial role of biofilms in the success of different pathogenic bacteria in infecting different hosts is well documented, but whether biofilms influence the interaction between beneficial bacteria and their host is largely unknown.
Bacillus subtilis is a model beneficial bacterium with the ability to display many distinct cell types under developmental control, including the ability to form robust and sophisticated biofilms. Interestingly, a recent study showed that planktonic B. subtilis modulates the longevity of the bacteriovorus nematode and model organism Caenorhabditis elegans independent of its role as a food source.
Worms fed on planktonic B. subtilis cells live longer (an approximately 15% increase in lifespan) than worms grown in the presence of other food sources, that is, E. coli. Because of the limited understanding of the effect of biofilm formed by beneficial gut bacteria on host health, authors determined whether the biofilm of B. subtilis might represent a novel anti-aging agent for improving host longevity.
Authors show that formation of Bacillus subtilis biofilms increases Caenorhabditis elegans lifespan. Biofilm-proficient B. subtilis colonizes the C. elegans gut and extends worm lifespan more than biofilm-deficient isogenic strains.
Two molecules produced by B. subtilis — the quorum-sensing pentapeptide CSF and nitric oxide (NO) — are sufficient to extend C. elegans longevity. When B. subtilis is cultured under biofilm-supporting conditions, the synthesis of NO and CSF is increased in comparison with their production under planktonic growth conditions.
Researchers further show that the prolongevity effect of B. subtilis biofilms depends on the DAF-2/DAF-16/HSF-1 signalling axis and the downregulation of the insulin-like signalling (ILS) pathway.
Microbiota increases lifespan in worms!
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