Changes in Antibiotic Resistance Gene Levels in Soil after Irrigation with Treated Wastewater: A Comparison between Heterogeneous Photocatalysis and Chlorination

Abstract

Wastewater (WW) reuse is expected to be increasingly indispensable in future water management to mitigate water scarcity. However, this increases the risk of antibiotic resistance (AR) dissemination via irrigation. Herein, a conventional (chlorination) and an advanced oxidation process (heterogeneous photocatalysis (HPC)) were used to disinfect urban WW to the same target of Escherichia coli <10 CFU/100 mL and used to irrigate lettuce plants ( Lactuca sativa ) set up in four groups, each receiving one of four water types, secondary WW (positive control), fresh water (negative control), chlorinated WW, and HPC WW. Four genes were monitored in water and soil, 16S rRNA as an indicator of total bacterial load, intI1 as a gene commonly associated with anthropogenic activity and AR, and two AR genes bla OXA-10 and qnrS . Irrigation with secondary WW resulted in higher dry soil levels of intI1 (from 1.4 × 10 4 copies/g before irrigation to 3.3 × 10 5 copies/g after). HPC-treated wastewater showed higher copy numbers of intI1 in the irrigated soil than chlorination, but the opposite was true for bla OXA-10 . The results indicate that the current treatment is insufficient to prevent dissemination of AR markers and that HPC does not offer a clear advantage over chlorination.

Abundance and Dynamic Distribution of Antibiotic Resistance Genes in the Environment Surrounding a Veterinary Antibiotic Manufacturing Site

“…Residual antibiotics and ARGs can enter into drinking water systems, which in turn increase the possibility of antibiotic resistance dissemination among the population [ 18 ]. In addition, antibiotics and ARGs will be transferred to soils through crop irrigation [ 19 ], composting of animal feces [ 20 ] etc., thus entering the food chain, posing threats to human health [ 21 , 22 , 23 ].…”

Environmental effects and risk control of antibiotic resistance genes in the organic solid waste aerobic composting system: A review

“…ARGs are widely present in natural environments, including aerosols, soil, surface water, sewage, and oligotrophic Antarctic (Li et al, 2015;Zhang et al, 2015;Wang et al, 2016a;Li et al, 2020b;Zammit et al, 2020). However, the release of ARGs from anthropogenic sources has exacerbated ARG accumulation in the environment (Li et al, 2015).…”

Tailoring CRISPR-Cas Immunity for the Degradation of Antibiotic Resistance Genes

“…However, detection of various types of ARGs has been reported in and near wastewater treatment facilities, [4][5][6][7] indicating them potential sources for ARGs at the same time. To address this rising challenge, the fate of ARGs in engineered and natural systems has been interrogated, [8][9][10][11][12][13] and remediation methods have been developed. [14][15][16] Most of the current methods remove ARGs as biomolecules based on the physiochemistry of DNAs.…”

“…It, unfortunately, seems inevitable as the ARGs may be required and accumulate for the removal of antibiotics in the wastewater from pharmaceutical industries, hospitals, or even municipal sewerage systems, leading to a dilemma in addressing ARG problems. To tackle this challenge, environmental scientists have interrogated the fate of ARGs in engineered and natural systems (9)(10)(11)(12), and have been developing remediation methods (13)(14)(15). For current environmental applications, most of the methods remove ARGs as biomolecules based on the physiochemistry of DNAs (13).…”