Massively parallel mutant selection identifies genetic determinants ofPseudomonas aeruginosacolonization ofDrosophila melanogaster

Abstract

Pseudomonas aeruginosais recognized for its ability to colonize diverse habitats and cause disease in a variety of hosts, including plants, invertebrates, and mammals. Understanding how this bacterium is able to occupy wide-ranging niches is important for deciphering its ecology. We used transposon sequencing (Tn-Seq, also known as INSeq) to identify genes inP. aeruginosathat contribute to fitness during colonization ofDrosophila melanogaster. Our results reveal a suite of critical factors, including those that contribute to polysaccharide production, DNA repair, metabolism, and respiration. Comparison of candidate genes with fitness determinants discovered in previous studies ofP. aeruginosaidentified several genes required for colonization and virulence determinants that are conserved across hosts and tissues. This analysis provides evidence for both the conservation of function of several genes across systems, as well as host-specific functions. These findings, which represent the first use of transposon sequencing of a gut pathogen inDrosophila, demonstrate the power of Tn-Seq in the fly model system and advance existing knowledge of intestinal pathogenesis byD. melanogaster,revealing bacterial colonization determinants that contribute to a comprehensive portrait ofP.aeruginosalifestyles across habitats.ImportanceDrosophila melanogasteris a powerful model for understanding host-pathogen interactions. Research with this system has yielded notable insights into mechanisms of host immunity and defense, many of which emerged from analysis of bacterial mutants defective for well-characterized virulence factors. These foundational studies – and advances in high-throughput sequencing of transposon mutants – support unbiased screens of bacterial mutants in the fly. To investigate mechanisms of host-pathogen interplay and exploit the tractability of this model host, we used a high-throughput, genome-wide mutant analysis to find genes that enable a pathogen,P. aeruginosa, to colonize the fly. Our analysis reveals critical mediators ofP. aeruginosaestablishment in its host, some of which are required across fly and mouse systems. These findings demonstrate the utility of massively parallel mutant analysis and provide a platform for aligning the fly toolkit with comprehensive bacterial genomics.