Beneficial bacteria have been shown to affect host longevity, but the molecular mechanisms mediating such effects remain largely unclear. Here we 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. We 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.
Probiotics are live microorganisms that have beneficial effects on host health, including extended lifespan, when they are administered or present in adequate quantities. However, the mechanisms by which probiotics stimulate host longevity remain unclear and very poorly understood. In a recent study (Nat. Commun. 8, 14332 (2017) doi: 10.1038/ncomms14332), we used the spore-forming probiotic bacterium Bacillus subtilis and the model organism Caenorhabditis elegans to study the mechanism by which a probiotic bacterium affects host longevity. We found that biofilm-proficient B. subtilis colonized the C. elegans gut and extended the worm lifespan significantly longer than did biofilm-deficient isogenic strains. In addition to biofilm proficiency, the quorum-sensing pentapeptide CSF and nitric oxide (NO) represent the entire B. subtilis repertoire responsible for the extended longevity of C. elegans. B. subtilis grown under biofilm-supporting conditions synthesized higher levels of NO and CSF than under planktonic growth conditions, emphasizing the key role of the biofilm in slowing host aging. Significantly, the prolongevity effect of B. subtilis was primarily due to a downregulation of the insulin-like signaling system that precisely is a key partaker in the healthy longevity of human centenarians. These findings open the possibility to test if the regular consumption of B. subtilis incorporated in foods and beverages could significantly extend human life expectancy and contribute to stop the development of age-related diseases.Why do people die? Leaving aside deaths produced in violent events such as accidents, armed robberies, terrorist attacks and armed conflicts, people die because of two "natural" causes: disease and/or aging. In the first case we state that a person died as a consequence of a particular disease process, in the second case we state that a person died because he/she aged. During the past century, scientists fought the first cause of natural death: human diseases. In 1918 the influenza pandemic or Spanish flu (1918)(1919) infected 500 million people around the world, killed 50 to 100 million people and produced a drop of twelve years in life expectancy. Today is almost impossible to think of that amount of people killed because the outbreak of a pandemic with the characteristics of the Spanish flu. This is because humankind developed medicines, antibiotics, vaccines and protocols to prevent and control disease dissemination. For instance, the recent West African Ebola outbreak (2013 -2016) was contained in the countries where it originated and caused around 11,000 deaths, a significant number of deaths but far below the ones produced by the 1918 flu pandemic. If the 2013 Ebola outbreak would have appeared one century ago it would had produced deaths by hundreds of millions. Therefore, we could agree on the point that scientists have given a hard blow to the first cause of natural death: disease, mainly infectious diseases.A dramatic increase of 5 years in life expectancy happened between 2000 a...
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