Pseudomonas Aeruginosa Biofilm Dynamics and UV Stress Responses

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen renowned for its ability to form robust, surface‐attached communities known as biofilms. These structures comprise bacterial cells embedded in a self‐produced extracellular polymeric substance (EPS) matrix, which confers enhanced tolerance to environmental insults, antimicrobial agents and host immune defences. Biofilm development follows a coordinated series of stages: initial attachment, microcolony formation, maturation into a three‐dimensional architecture and, ultimately, dispersal. Within mature biofilms, physiological heterogeneity arises through nutrient and oxygen gradients, giving rise to distinct subpopulations including metabolically active cells, dormant persister phenotypes and cells poised for dispersal.

Exposure to ultraviolet (UV) radiation represents a potent abiotic stressor that inflicts DNA damage, generates reactive oxygen species (ROS) and perturbs cellular membranes. P. aeruginosa biofilms respond to UV challenge by upregulating DNA repair pathways such as nucleotide excision repair and photoreactivation, by modulating EPS composition and by activating global regulators including alternative sigma factors and small RNAs. UV‐induced oxidative stress further triggers expression of antioxidant defence enzymes. The interplay between UV stress signalling and biofilm regulatory circuits influences community resilience, dispersal dynamics and the emergence of resistant variants. Understanding these processes is critical for optimising disinfection strategies, designing anti‐biofilm surfaces and mitigating chronic infections associated with medical devices and industrial biofouling.

Research from Nature Portfolio

Recent studies have revealed the structural adaptations of P. aeruginosa biofilms under sublethal UV doses by employing high‐resolution imaging and single‐cell tracking. These investigations showed that UV exposure induces a shift in EPS architecture, with increased incorporation of deacetylated alginate that enhances matrix stiffness and impedes deeper UV penetration. Concurrently, activation of the alternative sigma factor AlgU was shown to coordinate expression of protective polysaccharides and DNA repair enzymes, linking matrix remodelling directly to UV tolerance.

Further work has identified a network of small regulatory RNAs that modulate biofilm dispersal in response to UV‐induced DNA damage. These noncoding RNAs tune cyclic‐di‐GMP levels by targeting diguanylate cyclases, thereby triggering cells at the biofilm periphery to adopt a planktonic lifestyle. This dispersal mechanism enables escape from hostile UV environments and facilitates colonisation of new niches.

Pseudomonas Aeruginosa Biofilm Dynamics and UV Stress Responses publication trend

The graph below shows the total number of articles in pseudomonas aeruginosa biofilm dynamics and uv stress responses across all publications each year (not limited to Nature Index journals).

Technical terms

Biofilm: A structured microbial community enclosed in an extracellular matrix that adheres to biotic or abiotic surfaces.

Extracellular polymeric substance (EPS): A hydrated network of polysaccharides, proteins and nucleic acids that surrounds biofilm cells and mediates adhesion and protection.

Persister cells: Dormant bacterial subpopulations within biofilms that exhibit transient tolerance to stress and antimicrobial agents.

Cyclic-di-GMP: A bacterial second messenger that regulates transitions between motile and sessile lifestyles and controls biofilm formation.

Photoreactivation: A light‐dependent DNA repair mechanism mediated by photolyase enzymes that reverses UV‐induced pyrimidine dimers.

Alternative sigma factor (AlgU): A subunit of RNA polymerase that redirects transcription to stress‐responsive genes, including those for matrix production and DNA repair.

References

1. Evaluation of Viable Cells in Pseudomonas aeruginosa Biofilmsby Colony Count and Live/Dead Staining.. Bio-protocol (2020).
2. Production and purification of protease produced by UV-mutated Pseudomonas aeruginosa. Journal of Emergency Medicine Trauma and Acute Care (2024).