Lactobacillus plantarum favors the early emergence of fit and fertile adult Drosophila upon chronic undernutrition

Abstract

Animals are naturally surrounded by a variety of microorganisms with which they constantly interact. Among these microbes, some live closely associated with a host and form its microbiota. These communities are now extensively studied, owing to their contributions to shaping various aspects of animal physiology. One of these commensal species, Lactobacillus plantarum, and in particular the L.p.WJL strain, has been shown to promote the growth of Drosophila larvae upon nutrient scarcity, allowing earlier metamorphosis and adult emergence compared to axenic individuals. As for many insects, conditions surrounding the post-embryonic development dictate key adult life history traits in Drosophila, and adjusting developmental timing according to the environment is essential for adult fitness. Thus, we wondered if the growth acceleration induced by L.p.WJL in a context of poor nutrition could adversely impact the fitness of Drosophila adults. Here we show that the L.p.WJL-mediated acceleration of growth is not deleterious; adults emerging after an accelerated development are as fit as their axenic siblings. Additionally, L.p.WJL's presence even leads to a lifespan extension in nutritionally challenged males. These results demonstrate that L.p.WJL is a beneficial partner for Drosophila melanogaster through its entire life cycle. Thus commensal bacteria allow the earlier emergence and longer survival of fit and fertile individuals and might represent one of the factors contributing to the ecological success of Drosophila.