Pseudomonas aeruginosa is capable of natural transformation in biofilms

Abstract

Natural transformation is a mechanism that enables competent bacteria to acquire naked, exogenous DNA from the environment. It is a key process that facilitates the dissemination of antibiotic resistance and virulence determinants throughout bacterial populations. <i>Pseudomonas aeruginosa</i> is an opportunistic Gram-negative pathogen that produces large quantities of extracellular DNA (eDNA) that is required for biofilm formation. <i>P. aeruginosa</i> has a remarkable level of genome plasticity and diversity that suggests a high degree of horizontal gene transfer and recombination but is thought to be incapable of natural transformation. Here we show that <i>P. aeruginosa</i> possesses homologues of all proteins known to be involved in natural transformation in other bacterial species. We found that <i>P. aeruginosa</i> in biofilms is competent for natural transformation of both genomic and plasmid DNA. Furthermore, we demonstrate that type-IV pili (T4P) facilitate but are not absolutely essential for natural transformation in <i>P. aeruginosa</i>.