Objective
Identify genes that are involved in phenotypic adaptation against antimicrobials in biofilms.
Inactivation of individual genes by mutation is a powerful tool for the identification of gene function. By screening a Pseudomonas aeruginosa mutant library, we identified several genes that are related to AMR during biofilm formation, which could be used as targets for drug development. For instance, our results showed that the cbrB gene, coding for a transcriptional regulator important for the use of various carbon and nitrogen sources, is essential for biofilm formation and tolerance to several antibiotics. Our approach also highlighted several genes that are specifically used by P. aeruginosa in the context of biofilms and cystic fibrosis infections to ensure survival. These hits could serve as markers to predict the feasibility of antibiotic treatment through quick genomic characterization of clinical strains. In summary, our work provides new insights in our understanding of P. aeruginosa survival to antibiotics and reveals new leads for innovative therapeutic strategies.
Schematic representation of bacteria, shown as rods, in a biofilm. While the wild-type strain in the top row possess all genes, one gene is deleted in the mutant. A mutant library contains about 6000 mutants; one for each gene in the genome of Pseudomonas aeruginosa. The wild-type survives the stress imposed by the antibiotic and the antimicrobial coating, while the mutant does not. This means that the gene deleted in the mutant is required for stress survival Source: Jules Valentin, EMPA
Diagram of the screening protocol used to assess the biofilm tolerance to antibiotics of Pseudomonas aeruginosa. The assay is performed in 96-well plates with a mutant library containing about 6000 mutants; one for each gene in the genome of P. aeruginosa. Here, a side-view of the well is represented to show the behavior of biofilms formed by resistant and sensitive strains. The resistant strain survives the stress imposed by the antibiotic, while the mutant does not. Source: EMPA