Biofilm inactivation using LED systems emitting germicidal UV and antimicrobial blue light

Area of Science:

• Environmental Microbiology
• Water Treatment Technologies
• Disinfection Science

Background:

• Biofilms in water systems pose significant risks to drinking water safety by harboring pathogens.
• Non-chemical disinfection methods are sought as alternatives to traditional water treatment.
• Light-based disinfection, including germicidal ultraviolet (UV) and antimicrobial blue light (aBL), shows promise for biofilm control.

Purpose of the Study:

• To investigate the efficacy of UV and aBL in inactivating Pseudomonas aeruginosa and mixed-culture biofilms.
• To compare the performance of a low-pressure (LP) UV lamp (254 nm), a UV light-emitting diode (LED) (270 nm), and an aBL LED (405 nm).
• To assess the influence of surface material properties (polycarbonate, PTFE, PVC) on light-based biofilm inactivation.

Main Methods:

• Development of pure-culture and mixed-culture biofilms on polycarbonate, PTFE, and PVC materials.
• Exposure of biofilms to three distinct light sources: LP UV lamp, UV LED, and aBL LED.
• Quantification of biofilm inactivation based on light fluence and material surface characteristics.

Main Results:

• All tested light devices demonstrated effective inactivation of both pure-culture and mixed-culture biofilms.
• UV devices (LP UV and UV LED) achieved significant inactivation at lower fluences ( >1 log reduction at 20 mJ/cm²).
• aBL LED required significantly higher fluences for substantial inactivation of pure-culture biofilms (maximum 3.8 ± 0.5 log reduction at >200,000 mJ/cm²).
• Biofilm inactivation varied across different surface materials, influenced by properties like roughness, hydrophobicity, and surface charge.

Conclusions:

• Light-based disinfection methods are effective for controlling biofilms in water systems.
• UV light offers efficient inactivation at lower energy doses compared to aBL.
• Surface material characteristics play a crucial role in the effectiveness of light-based biofilm disinfection, necessitating material-specific treatment considerations.