Project description:Purpose: Pseudomonas aeruginosa is a major cause of morbidity and mortality in patients with cystic fibrosis (CF). We provide an insight to the DNA auxotrophy of P. aeruginosa PASS4 isolate. Better understanding of P. aeruginosa adaptations in the CF lung environment can have a great impact in the development of specialised treatment regimes aimed at the eradications of P. aeruginosa infections. Methods: P. aeruginosa strains PAO1 and PASS4 were grown in minimal medium with either L-Asparagine or DNA as a carbon source, in biological triplicates. RNA was extracted and sequenced on Illumina HiSeq 1000 platform. The sequence reads that passed quality filters were analyzed using EdgePro and DESeq packages, as well as the Rockhopper tool. Results: We mapped > 10 million paired sequence reads per sample to the genome of P. aeruginosa PAO1 and identified a total of 576 genes differentially expressed by PASS4 when grown in DNA (P value < 0.01, log2 fold-change 1< to < -1), with 322 genes upregulated and 254 genes downregulated. There were a total of 423 genes differentially expressed by PAO1 when grown in DNA (P value < 0.01, log2 fold-change 1< to <-1), with 359 genes upregulated and 64 genes downregulated . A total of 129 transcripts displayed similar expression patterns in both organisms, with 112 being upregulated and 17 down-regulated. Conclusions: Our study identified that P. aeruginosa PASS4 was a purine auxotroph. Purine auxotropy may represent a viable microbial strategy for adaptation to DNA rich environments such as the CF lung.
Project description:Taxonomic outliers of Pseudomonas aeruginosa recently emerged as infectious for humans. Here we present the first analysis of a hyper-virulent isolate that cause hemorrhagic pneumonia. We demonstrated that, in two sequential clones CLJ1 and CLJ3 recovered from a patient with chronic obstructive pulmonary disease undergoing antibiotic therapy, insertion of a mobile genetic element into the P. aeruginosa chromosome affected major virulence-associated phenotypes and led to increased resistance to antibiotics used to treat the patient. Our work reveals insertion sequences as major players in enhancing the pathogenic potential of a P. aeruginosa taxonomic outlier by modulating both the virulence and resistance to antimicrobials. This also explains the ability of this bacterium to adapt to an infected host and cause a serious disease.
