Different Long-Term Nutritional Regimens of Drosophila melanogaster Shape Its Microbiota and Associated Metabolic Activity in a Sex-Specific Manner

The dietary habits of fruit flies profoundly influence their fitness, morphology, and physiology yet the mechanisms underlying these effects remain incompletely understood. To address this gap, the relationship between dietary regimens and the composition and function of adult <i>Drosophila melanogaster</i> microbiota was investigated in the present study. The adult fly microbiota communities that were reared for long time on five different diets were characterized by means of 16S rRNA sequencing. Obtained results revealed distinct community structures associated with each dietary regimen, which was additionally corroborated through machine learning-based analysis. In general, sugar-rich diets correlate with microbial ecosystems of higher richness/diversity. Dominance of the phyla <i>Proteobacteria</i> and <i>Firmicutes</i> in the microbiota was confirmed irrespective of diet, with the varying proportions of the most abundant families: <i>Acetobacteraceae</i>, <i>Lactobacillaceae</i>, <i>Moraxellaceae</i>, <i>Bradyrhizobiaceae</i>, and <i>Leucostonocaceae</i>. Bacterial families of lower abundance also emerged as differentially present among the studied fly groups. Additionally, functional prediction provided initial clues into how nutrient availability might modulate the metabolic traits of adult fly microbiota in a sex-specific manner to meet host metabolic needs. Overall, the presented findings highlight the intricate interplay between diet, microbiota composition, and host phenotype in fruit flies, underscoring the importance of diet as a determinant of host-microbiota interactions.