H2O2 and/or TiO2 photocatalysis under UV irradiation for the removal of antibiotic resistant bacteria and their antibiotic resistance genes

Abstract

Inactivating antibiotic resistant bacteria (ARB) and removing antibiotic resistance genes (ARGs) are very important to prevent their spread into the environment. Previous efforts have been taken to eliminate ARB and ARGs from aqueous solution and sludges, however, few satisfying results have been obtained. This study investigated whether photocatalysis by TiO₂ was able to reduce the two ARGs, mecA and ampC, within the host ARB, methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. The addition of H₂O₂ and matrix effect on the removal of ARB and ARGs were also studied. TiO₂ thin films showed great effect on both ARB inactivation and ARGs removal. Approximately 4.5-5.0 and 5.5-5.8 log ARB reductions were achieved by TiO₂ under 6 and 12mJ/cm² UV₂₅₄ fluence dose, respectively. For ARGs, 5.8 log mecA reduction and 4.7 log ampC reduction were achieved under 120mJ/cm² UV₂₅₄ fluence dose in the presence of TiO₂. Increasing dosage of H₂O₂ enhanced the removal efficiencies of ARB and ARGs. The results also demonstrated that photocatalysis by TiO₂ was capable of removing both intracellular and extracellular forms of ARGs. This study provided a potential alternative method for the removal of ARB and ARGs from aqueous solution.

Keywords: Antibiotic resistance genes (ARGs); Antibiotic resistant bacteria (ARB); Photocatalysis; Removal; TiO(2).