Abstract

In this work we use the fruit fly Drosophila melanogaster as a model to identify bacterial genes that help bacteria to persist in their animal hosts. Early work on this model system established that dietary replenishment drives the composition of the D. melanogaster gut microbiota, and subsequent research has shown that some bacterial strains can colonize the fly for much longer than the flow of bulk diet through the gut. In this work we reveal that bacterial genes influence bacterial persistence by studying the correlation between bacterial genotype and persistence in the D. melanogaster gut microbiota. We performed an initial assay with 7 bacterial strains to establish that different bacterial strains persist differently independent of ingestion in the fly. We then repeated the assay with 41 different strains of bacteria in order to perform a metagenome wide association (MGWA) to find distinct bacterial genes that are significantly correlated with persistence. Based on the MGWA, we tested if 44 mutants from 6 gene categories affect bacterial persistence in the flies. We identified that transposon insertions in four flagellar genes (fliF, flgH, fliI, and flgE), one urea carboxylase gene, one phosphatidyl inositol gene, one bacterial secretion gene, and one antimicrobial peptide (AMP) resistance gene each significantly lowered colonization forming units (CFUs) that resulted from plating the gut content in Drosophila melanogaster. Follow-up experiments with the flagellar gene mutants revealed that each significant flagellar mutant was non-motile compared with the wild type. Taken together, these results reveal that there are bacterial genes that are involved in mechanisms, like bacterial motility, that help bacteria to persist in the fly gut.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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