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Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Decoupled sulfonamide biodegradation and resistance gene responses in leachate treatment sludge
Kaiyi Wu1, Peiyao Yun2, Dongjing Zhou2
1School of Agriculture and Biotechnology, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen 518107, China; The Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510530, China.
Abstract:
Municipal solid waste leachate is an important sink of sulfonamides and resistance genes, yet the coupling between antibiotic removal and resistance-associated risks across exposure levels in leachate sludge remained unclear. Here, sludge from the primary (PNS) and secondary (SNS) nitrification units of a full-scale leachate treatment plant were exposed to a mixture of sulfadiazine (SDZ), sulfamethoxazole (SMX), and trimethoprim (TMP) at 10 and 500 µg/l for each compound in batch experiments. At 10 µg/l, PNS and SNS removed 73.4 % of SDZ and 95.0 % of SMX, while TMP concentrations decreased below the quantification limit by day 5. Their removal efficiencies decreased at 500 µg/l. Metagenomic profiles indicated greater biodegradation-related potential under low-level exposure but reduced catabolic potential under high-level exposure. Meanwhile, 10 µg/l exposure increased the relative abundances of sulfonamide resistance genes and intI1, indicating the enrichment of resistance-associated genes and increased genetic mobility potential during the 14-day incubation. Additionally, SNS exhibited stronger short-term changes in resistance-associated genes and bacterial community composition than PNS. An exploratory cross-plant comparison suggested greater dissimilarity in resistance-related than biodegradation-related profiles. Apparently,antibiotic biodegradation potential and resistance-associated risks were not coupled in leachate treatment systems. These results will shed some lights into standardized antibiotic-associated risk assessments of leachate biological treatment systems.
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