Abstract
Introduction. Pseudomonas aeruginosa grows in extracellular DNA (eDNA)-enriched biofilms and infection sites. eDNA is generally considered to be a structural biofilm polymer required for aggregation and biofilm maturation. In addition, eDNA can sequester divalent metal cations, acidify growth media and serve as a nutrient source.Aim. We wanted to determine the genome-wide influence on the transcriptome of planktonic P. aeruginosa PAO1 grown in the presence of eDNA.Methodology. RNA-seq analysis was performed to determine the genome-wide effects on gene expression of PAO1 grown with eDNA. Transcriptional lux fusions were used to confirm eDNA regulation and to validate phenotypes associated with growth in eDNA.Results. The transcriptome of eDNA-regulated genes included 89 induced and 76 repressed genes (FDR<0.05). A large number of eDNA-induced genes appear to be involved in utilizing DNA as a nutrient. Several eDNA-induced genes are also induced by acidic pH 5.5, and eDNA/acidic pH promoted an acid tolerance response in P. aeruginosa. The cyoABCDE terminal oxidase is induced by both eDNA and pH 5.5, and contributed to the acid tolerance phenotype. Quantitative metal analysis confirmed that DNA binds to diverse metals, which helps explain why many genes involved in a general uptake of metals were controlled by eDNA. Growth in the presence of eDNA also promoted intracellular bacterial survival and influenced virulence in the acute infection model of fruit flies.Conclusion. The diverse functions of the eDNA-regulated genes underscore the important role of this extracellular polymer in promoting antibiotic resistance, virulence, acid tolerance and nutrient utilization; phenotypes that contribute to long-term survival.
Highlights
Bacteria encounter the presence of extracellular DNA when growing as biofilms and during interactions with immune cells [1]
Bacteria are likely exposed to extracellular DNA (eDNA) in many infection sites, where microbes encounter neutrophil extracellular traps (NETs) [3]
We performed RNA-seq analysis of P. aeruginosa PAO1 in the absence and presence of extracellular DNA (0.75%; 7.5 mg/ml) added to basal medium 2 (BM2) defined medium in order to identify the global profile of genes regulated by eDNA
Summary
Bacteria encounter the presence of extracellular DNA (eDNA) when growing as biofilms and during interactions with immune cells [1]. Bacteria are likely exposed to eDNA in many infection sites, where microbes encounter neutrophil extracellular traps (NETs) [3]. NETs are an ejected lattice of chromosomal DNA that is enmeshed with numerous antimicrobial proteins from neutrophil granules that function to trap and kill numerous microbial organisms [3]. We are beginning to appreciate the functions of extracellular DNA on bacterial physiology through understanding its role in bacterial biofilms. Extracellular DNA is a ubiquitous biofilm matrix polymer that has been shown to promote attachment and biofilm formation in most bacterial species tested [7]. Extracellular DNA coordinates the migration of P. aeruginosa aggregates in interstitial biofilms formed on semisolid media [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
