Uncovering the molecular mechanisms of the Pseudomonas aeruginosa PA14 response to myxobacterial predation

Abstract

Myxobacteria are Gram-negative bacteria, notable for their predatory and antimicrobial activities, which dictate the outcomes of their interactions with neighbouring organisms. They are abundant and widespread in nature, and can significantly affect the microbiome of an environment. We hypothesise that there are underlying molecular mechanisms in prey specieswhich govern the prey’s susceptibility/resistance to the antimicrobial activity of myxobacteria. In this work we attempt to define the mechanisms by which Pseudomonas aeruginosa PA14 resists predation bythe model myxobacterium Myxococcus xanthus. Pseudomonas aeruginosa is an opportunistic pathogen of humans and plants. With the rise in antibiotic resistant organisms, Pseudomonas spp. are categorised as World Health Organisation priority 1 antibiotic-resistant bacteria and are our prey of choice in this study. In collaboration with Dr N. Tucker (Strathclyde), and using a strain of M. xanthus expressing mCherry (courtesy of E. Hoiczyk, Sheffield), we developed 96-well plate assays of predation which measured the optical density of both predator and prey and the florescence of predator at different point intervals. Predation was assayed againsta library of approximately 5700 PA14 mutants to identify strains with increased/decreased susceptibility to predation. Responses of PA14 mutants varied with time and between mutants, allowing us to create a shortlist of candidate genes involved in the prey response to predation. We are currently performing a preliminary analysis of the data using the Integrated Genomic Viewer and Circos plots to assess the genomic organisation of the prey genes that influence susceptibility and resistance to predation.