%0 Journal Article
%T Phenotypic and Transcriptional Responses of Pseudomonas aeruginosa Biofilms to UV-C Irradiation via Side-Emitting Optical Fibers: Implications for Biofouling Control.
%A Zhao Z
%A Luo YH
%A Wang TH
%A Sinha S
%A Ling L
%A Rittmann B
%A Alvarez P
%A Perreault F
%A Westerhoff P
%J Environ Sci Technol
%V 57
%N 41
%D 2023 10 17
%M 37802050
%F 11.357
%R 10.1021/acs.est.3c04658
%X Biofilms give rise to a range of issues, spanning from harboring pathogens to accelerating microbial-induced corrosion in pressurized water systems. Introducing germicidal UV-C (200-280 nm) irradiation from light-emitting diodes (LEDs) into flexible side-emitting optical fibers (SEOFs) presents a novel light delivery method to inhibit the accumulation of biofilms on surfaces found in small-diameter tubing or other intricate geometries. This work used surfaces fully submerged in flowing water that contained Pseudomonas aeruginosa, an opportunistic pathogen commonly found in water system biofilms. A SEOF delivered a UV-C gradient to the surface for biofilm inhibition. Biofilm growth over time was monitored in situ using optical conference tomography. Biofilm formation was effectively inhibited when the 275 nm UV-C irradiance was ≥8 μW/cm2. Biofilm samples were collected from several regions on the surface, representing low and high UV-C irradiance. RNA sequencing of these samples revealed that high UV-C irradiance inhibited the expression of functional genes related to energy metabolism, DNA repair, quorum sensing, polysaccharide production, and mobility. However, insufficient sublethal UV-C exposure led to upregulation genes for SOS response and quorum sensing as survival strategies against the UV-C stress. These results underscore the need to maintain minimum UV-C exposure on surfaces to effectively inhibit biofilm formation in water systems.