Comparative Analysis of the Native Microbiota in gammaCop Mutant versus Wild-Type Genetic Background of Drosophila melanogaster

Drosophila melanogaster represents a genetically tractable model for studying the mechanisms used by the infectious microorganisms to colonize healthy individuals. Since native microbiota plays an important role in host resistance to colonization, our aim was to study the influence of the genetic background on D. melanogaster microbiota diversity, as a prerequisite for using different lines in experimental infection challenge assays. In this purpose, we have assessed the microbiota of D. melanogaster wild-type Oregon and gammaCop (gamma Cop) mutants males, by genetic and culture dependent methods. The cultivable fly-derived microbiota was estimated by viable cell counts. Each morphological type of bacterium was considered for identification through biochemical tests. The diversity of the microbial communities was assessed also by amplified ribosomal DNA restriction analysis (ARDRA). Our study emphasizes that both wild-type and mutant D. melanogaster males harbor a low-diversity bacterial community, highlighting the potential of this system to dissect the complex cellular and molecular interactions that occur between a eukaryotic host and its microbiota. The commonly found taxa were primarily represented by Enterobacteriaceae family (Providencia sp., Serratia sp. and Escherichia sp.) and the Bacilli class. The ARDRA approach highlighted a prevalence of 75% of the Enterobacteriaceae, especially P. rettgeri and E. coli, followed by Lactobacillaceae and Enterococcaceae. The amount of the cultivable bacteria in D. melanogaster varied quantitatively among different genetic backgrounds, gradually decreasing from Oregon to heterozygous and homozygous gamma Cop(14a) males. Our results suggest that gamma Cop gene is involved in configuring the profile of native microbiota of D. melanogaster, an aspect that should be considered when wild-type versus specific mutant D. melanogaster lines are used as models in infectious pathogenesis experiments.