Probiotic Lactobacillus reuteri extends the lifespan of Drosophila melanogaster

Commensal microbes that reside in intestine of host with symbiotic relationship are well known to affect host fitness such as metabolism, obesity, and inflammation. Especially, lactic acid bacteria which excrete lactic acid as the main fermentation product are known as ‘probiotics’, having a beneficial effect in host. Lactobacillus reuteri is one of lactic acid bacteria isolated from human breast milk. Although L. reuteri has anti-microbial and anti-inflammatory activity that are sometimes linked to increased lifespan, there are no trials to test the longevity regulating effect of L. reuteri in animal model. To test it, we used freeze-dried powder of Lactobacillus reuteri offered by Wedea Inc. in South Korea. We investigated the anti-aging effects of L. reuteri including lifespan and physiology in Drosophila melanogaster . We measured the lifespan of flies suppling with L. reuteri at 0, 50, 100, or 250 μg/ml and found that L. reuteri significantly increased the mean lifespan of fruit flies. Because the lifespan extension effect of L. reuteri is most effective at 100 μg/ml, we selected 100 μg/ml as optimal concentration of L. reuteri. The lifespan of organisms is affected by several factors such as the reduction of food intake and reproductive output. Thus, we measured feeding amount and fecundity in L. reuteri -treated flies to determine whether the lifespan-extending effect of L. reuteri was because of change of physiology. L. reuteri did not reduce the feeding amount or fecundity, indicating that increased lifespan by L. reuteri is the direct effect of bacteria, not by feeding or reproductive artifacts. However, long-term L. reuteri -treated groups showed the reduced body weight compared to controls. Interestingly, L. reuteri supplementation decreased the resistance to oxidative stress and starvation stress in fruit fly. In further study, we will study the relationship between dietary restriction and L. reuteri and the mechanisms of longevity effect of L. reuteri. We suggest that L. reuteri can be used as worthy probiotics and anti-aging agent.