Molecular ecological insights into the synergistic response mechanism of nitrogen transformation, electron flow and antibiotic resistance genes in aerobic activated sludge systems driven by sulfamethoxazole and/or trimethoprim stresses

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2024-11-24 DOI:10.1016/j.watres.2024.122853

Xiao-Yan Fan , Zhong-Xing Zhang , Na Li , Xing Li

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Abstract

The prevalence of antibiotics poses a serious challenge to biological nitrogen removal in wastewater. In this study, the effects of sulfamethoxazole and/or trimethoprim (15 mg/L∼30 mg/L) on treatment performance, nitrogen transformation and antibiotic resistance genes (ARGs) were investigated in aerobic activated sludge systems to elucidate the metabolic mechanism under high antibiotic stress. 15 mg/L single antibiotic stress improved total nitrogen removal performance due to the persistence of nitrifiers and enrichment of denitrifiers, with an optimum removal efficiency of 96.5 %. Up-regulation of all denitrifying genes, coupled with enhanced electron transfer of Complex II and III, contributed to the emergence of aerobic denitrification. The increased expression of antioxidant genes also alleviated intracellular pressure. Whereas combined antibiotic stress induced the significant down-regulation of denitrifying bacteria and genes (nirKS and nosZ), and suppressed the electron supply for denitrification by restraining genes related to Complex Ⅰ and energy supply by tricarboxylic acid cycle, driving the collapse of activated sludge system, with ammonia and total nitrogen removal efficiencies dropping to below 40 % and 20 %, respectively. The dominant genera in system changed from TM7a to Thiothrix and Sphaerotilus with increasing antibiotic concentration and type. Moreover, antibiotic stress promoted a slight enrichment of ARGs, especially those encoding efflux mechanisms. Cooperative relationships (> 93 %) dominated among ARGs, and Klebsiella was identified as the crucial host. ARGs regulating antibiotic efflux were more likely to be co-expressed with functional genes. These results may provide a theoretical basis for establishing promising strategies to mitigate antibiotic-caused process deterioration.

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对磺胺甲噁唑和/或三甲氧苄啶胁迫下好氧活性污泥系统中氮转化、电子流和抗生素抗性基因协同响应机制的分子生态学见解

抗生素的流行对废水中的生物脱氮提出了严峻的挑战。本研究考察了磺胺甲噁唑和/或三甲氧苄啶（15 mg/L∼30 mg/L）对好氧活性污泥系统处理性能、氮转化和抗生素耐药基因（ARGs）的影响，以阐明高抗生素胁迫下的代谢机制。15 毫克/升的单一抗生素胁迫提高了总氮去除率，原因是硝化细菌的持续存在和反硝化细菌的富集，最佳去除率为 96.5%。所有反硝化基因的上调，加上复合体 II 和 III 电子传递的增强，促进了需氧反硝化的出现。抗氧化基因表达的增加也减轻了细胞内的压力。而联合抗生素胁迫则诱导反硝化细菌和基因（nirKS 和 nosZ）的显著下调，并通过抑制与复合体Ⅰ相关的基因和三羧酸循环的能量供应来抑制反硝化的电子供应，导致活性污泥系统崩溃，氨氮和总氮的去除率分别降至 40% 和 20% 以下。随着抗生素浓度和种类的增加，系统中的优势菌属从 TM7a 变为 Thiothrix 和 Sphaerotilus。此外，抗生素胁迫促进了 ARGs 的轻微富集，尤其是那些编码外排机制的 ARGs。ARGs之间的合作关系（> 93%）占主导地位，克雷伯氏菌被确定为关键宿主。调节抗生素外流的 ARGs 更有可能与功能基因共同表达。这些结果可为制定有前景的策略以缓解抗生素导致的工艺退化提供理论依据。

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.