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bioRxiv2016

Lactobacillus plantarum is a pathobiont for adult Drosophila.

The microbiome of Drosophila promotes intestinal stem cell division through evolutionarily conserved biochemical pathways. As such, axenic flies have lower rates of gut stem cell division than age-matched wild type counterparts. Additionally, flies with a full consortium of symbiotic bacteria are shorter lived than those maintained in the absence of a microbiome. However, we do not know if stem cell division is essential for symbiont-dependent regulation of adult fly lifespan. To determine if individual symbionts cause aging-dependent death in Drosophila, we examined the impacts of common symbionts on host longevity. In this study, we found that mono-association of adult Drosophila with Lactobacillus plantarum, a widely reported fly symbiont, and member of the probiotic Lactobacillus genus, curtails adult longevity relative to germ-free counterparts. However, the effects of plantarum on lifespan were independent of intestinal aging. Instead, we found that association with plantarum causes an extensive intestinal pathology within the host, characterized by loss of intestinal stem cells, impaired epithelial renewal, and a gradual erosion of epithelial integrity. Our study uncovers an unknown aspect of Lactobacillus plantarum-Drosophila interactions, and establishes a simple model to characterize symbiont-dependent disruption of intestinal homeostasis.

Microbiology↗

bioRxiv2016

Comparative evaluation of the genomes of common bacterial members of the Drosophila intestinal community

Drosophila melanogaster is an excellent model to explore the molecular exchanges that occur between an animal intestine and their microbial passengers. For example, groundbreaking studies in flies uncovered a sophisticated web of host responses to intestinal bacteria. The outcomes of these responses define critical events in the host, such as the establishment of immune responses, access to nutrients, and the rate of larval development. Despite our steady march towards illuminating the host machinery that responds to bacterial presence in the gut, we know remarkably little about the microbial products that influence bacterial association with a fly host. To address this deficiency, we sequenced and characterized the genomes of three common Drosophila-associated microbes: Lactobacillus plantarum, Lactobacillus brevis and Acetobacter pasteurianus. In each case, we compared the genomes of Drosophila-associated strains to the genomes of strains isolated from alternative sources. This approach allowed us to identify molecular functions common to Drosophila-associated microbes, and, in the case of A. pasteurianus, to identify genes that are essential for association with the host. Of note, many of the gene products unique to fly-associated strains have established roles in the stabilization of host-microbe interactions. We believe that these data provide a valuable starting point for a more thorough examination of the microbial perspective on host-microbe relationships.

Microbiology↗