Photocatalytic inactivation of dual- and mono-species biofilms by immobilized TiO2

• Published in: Journal of photochemistry and photobiology. B, Biology Vol. 221; p. 112253
• Main Authors: Pablos, C., Govaert, M., Angarano, V., Smet, C., Marugán, J., Van Impe, J.F.M.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.08.2021; Elsevier BV
• Subjects: Bacteria; Biofilms; Colonization; Corrosion resistance; Deactivation; Food processing; Gram-negative bacteria; Gram-positive bacteria; Growth conditions; Immobilized TiO2; Inactivation; Listeria; Nanoparticles; Photocatalysis; Photosensitivity; Salmonella; Species; Technology transfer; TiO2 nanotubes; Titanium dioxide; Water treatment; Salmonella; Immobilized TiO2; TiO2 nanotubes; Biofilms; Listeria; Photocatalysis
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/j.jphotobiol.2021.112253

Biofilms formed by different bacterial species are likely to play key roles in photocatalytic resistance. This study aims to evaluate the efficacy of a photocatalytic immobilized nanotube system (TiO2-NT) (IS) and suspended nanoparticles (TiO2-NP) (SS) against mono- and dual-species biofilms developed by Gram-negative and Gram-positive strains. Two main factors were corroborated to significantly affect the biofilm resistance during photocatalytic inactivation, i.e., the biofilm-growth conditions and biofilm-forming surfaces. Gram-positive bacteria showed great photosensitivity when forming dual-species biofilms in comparison with the Gram-positive bacteria in single communities. When grown onto TiO2-NT (IS) surfaces for immobilized photocatalytic systems, mono- and dual-species biofilms did not exhibit differences in photocatalytic inactivation according to kinetic constant values (p > 0.05) but led to a reduction of ca. 3–4 log10. However, TiO2-NT (IS) surfaces did affect biofilm colonization as the growth of mono-species biofilms of Gram-negative and Gram-positive bacteria is significantly (p ≤ 0.05) favored compared to co-culturing; although, the photocatalytic inactivation rate did not show initial bacterial concentration dependence. The biofilm growth surface (which depends on the photocatalytic configuration) also favored resistance of mono-species biofilms of Gram-positive bacteria compared to that of Gram-negative in immobilized photocatalytic systems, but opposite behavior was confirmed with suspended TiO2 (p ≤ 0.05). Successful efficacy of immobilized TiO2 for inactivation of mono- and dual-species biofilms was accomplished, making it feasible to transfer this technology into real scenarios in water treatment and food processing. [Display omitted] •Effective inactivation of biofilms (BFs) by immobilized TiO2 (ca. 99–99.99%) at lab scale reactor.•Successful long-term control and prevention of biofilms accumulation in water treatment and food industry.•Photocatalytic (PC) process shows efficiency against mono- and dual-species BFs.•Gram-positive bacteria shows photosensitivity when forming dual-species BFs.•Gram-positive mono-specie BFs show higher resistance to inactivation than equivalent Gram-negative BFs.