Application of UVC and UVC based advanced disinfection technologies for the inactivation of antibiotic resistance genes and elimination of horizontal gene transfer activities: Opportunities and challenges

Abstract

Extensive application of antibiotics in the last few decades has promoted selective pressure to disseminate antibiotic resistance in the aquatic environment. Antibiotic-resistant genes (ARGs) and bacteria (ARB) were detected in wastewater, effluent from wastewater treatment plants (WWTPs), surface water, and finished water from drinking water treatment plants (DWTPs), and even in tap-water. Hence, the spread of antibiotic resistance has become a threat to public health. Traditional low-pressure UV lamps (LP UV) removed ARGs, but the fluences required to deactivate ARGs were very high. The efficiency of LP UV to diminish ARGs was more strongly correlated with adjacent thymine number rather than amplicon length since cyclobutane pyrimidine dimers (CPDs) are the significant lesions generated due to UVC-caused damage to DNA. Co-exposure of LP UV with other radicals in the UV based advanced oxidation processes (AOPs) exhibited some improvement in reducing concentrations of ARGs, specifically extracellular ARGs (eARGs). However, the exhaustion of radicals by various cellular components, such as cell membrane, cell wall, and cytoplasmic protein, has limited the widespread application of UV based AOPs. In LP UV-based AOPs, DNA damage induced by LP UV was identified as a major mechanism for eliminating ARG transformation. UVC light-emitting diodes (UVC LEDs) are increasingly being investigated for disinfection performances. 265 nm LED has shown better performance in controlling antibiotic resistance than 285 nm. Further researches are required to assess the performances of UVC LEDs and UVC LEDs based AOPs to deactivate ARGs.