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紫外光解削减水中抗生素抗菌活性及阻控抗性基因传播研究
Alternative TitleThe reduction of antibacterial activity of antibiotics in water and the elimination of transmission of antibiotic resistance genes by UV photolysis
丁养城
Subtype博士
Thesis Advisor王爱杰
2020-12
Degree Grantor中国科学院生态环境研究中心
Place of Conferral北京
Degree Name工学博士
Degree Discipline环境工程
Keyword紫外光解, 非生物 预处理, 抗生素, 抗菌活性 抗性基因 Uv Photolysis, Abiotic Pretreatment, Antibiotics, Antibacterial Activity, Antibiotic Resistance Genes
Abstract

    人类疾病 治疗和动物养殖 过程 产生的抗生素残留最终主要以各种废水的形式排放到污水处理厂 W WTP s 。 目前, 生物处理 仍 是 W WTP s 的主流处理工艺,但难降解抗生素产生的抗菌活性会严重抑制污 水处理 厂的生 物活性和功能,并存在 加剧 耐药菌 A RB 和抗性基因( A RG s )传播 的 风险。 因此,基于水中 A RG s的源头控制理念, 在生物处理 工艺 前 通过非生物预处理技术 削减 抗生素 的抗菌活性是 保障废水处理系统稳定运行 和阻控 A RG s 传播风险 的一条具有 前景的途径。
    在本研究中,通过与 热 水解和电 芬顿氧化技术比较,确定了 U V 光解 可以 作为 一种削减 抗生素抗菌活性 的 预处理 技术 ,具备分解多种抗生素和不 易 受共存有机物干扰的优势。经紫外光照射后, 5 种抗生素的抗菌活性 削减 与母体化合物浓度 下降 呈显著正相关。抗生素主要官能团的光解有助于 其 抗 菌 活性 的 削减 。脱氟是 削减 含氟取代基的抗生素(如氟苯尼考和氧氟沙星)抗菌活性的主要途径,而光诱导 β 内酰胺环的开环是 削减 β 内酰胺类抗生素(如头孢氨苄,阿莫西林和氨苄青霉素)抗菌活性的有效途径。这些结果表明, U V 光解可以作为一种 高 效的、有 应用前景 的抗生素抗菌活性源控制的预处理 方法 。
    为验证失去抗菌活性的抗生素同时失去了诱导 A RG s 产生的潜力, 构建了不同 U V 照射剂量 预处理 耦合好氧或厌氧生物过程处理含 氟苯尼考( F LO 模拟废水的体系 。 研究发现 UV 光解预处理显著降低了好氧和厌氧生物反应器中可检测A RG s 的多样性和丰 度 水平 特别是与目标抗生素 FLO密切相关的氯霉素类ARGs。 其中, 2 h 或以上的 U V 照射预处理使得后续生物处理过程的 floR丰度发生了 2个数量级 的下降 使其 与阴性对照组处于同一丰度水平( 10–3 copies /16S rRNA copies)。同时,好氧条件下 floR的相对丰度普遍高于厌氧条件,且同条件下位于质粒 DNA上的 floR丰度 高于染色体 DNA。 UV光解预处理还有效削减了染色体和质粒 DNA上 intI1的相对丰度,使其保持在空白对照组的丰度水平( (< 1.0  10–1 copies/16S rRNA copies)),从而降低了 floR 发生水平转移的潜在风险 。此外 ,足够剂量的 U V 光解预处理 有助于 污泥微生物群落的结构和组成 稳定,使其更接近无抗生素添加的对照实验组。在好氧和厌氧生物反应器中,作为 A RG s 潜在宿主的假单胞菌和Escherichia-Shigella的相对丰度 随 U V 照射剂量的增加而显著降低。
    针对单独U V 光解预处理 削减 水中抗生素抗菌活性 存在处理时间长,效率低等问题,通过 添加亚硫酸盐 引入还原性自由基,提高了 F LO 光解过程的脱氯和脱氟性能 。 研究发现 其 抗菌活性与脱氟率的相关性高于其 与 对 应 脱氯率 的 相 关性 。经过 12 min的 紫外 /亚硫酸盐 体系 UV/S 光解 预处理 其 后续生物处理系统中 FLO的特征 ARG floR)的相对丰度 处于 空白对照组的水平 6.52 ± 0.60 10–4 copies /16S rRNA copies)),与单独 UV光解预处理 20 min的 效果 相当。此外,过量溶解氧和 pH > 8的环境条件均不利于 FLO的分解 。 5 mg L–1以上的 腐殖酸共存 显著抑制 了 FLO的分解,但其他共存基质如蛋白质,葡萄糖和 HCO3–并未对目标抗生素 的 分解产生 显著 影响 。此外,同浓度下 的 eaq–和 H•淬灭 剂 NO2–共存 对 FLO分解的抑制作用显著高于 作 为 eaq–淬灭剂的 NO3–,这也表明 UV/S体系光解 FLO以 H•为主的还原脱氯脱氟过程 。此外, UV/S体系还适用于分解其他 氯霉素类 和 氟喹诺酮类 抗生素。 与 相同浓度 1 mM 添加剂 下的 UV/H2O2和UV/过硫酸盐 体系 相比 UV/S体系分解 FLO的速率常数 最大,而 且不 易 受共存有机物的影响 。

Other Abstract

    Antibiotic residues from human treatment and animal breeding are ultimately discharged to wastewater treatment plants (WWTPs) in the form of various wastewater. Engineered biological treatment systems are the mainstream treatment process of WWTPs. However, the antimicrobial activity produced by refractory antibiotics will seriously inhibit the biological activity and function of wastewater treatment plant, and further lead to the risk of transmission of antibiotic resistant bacteria (ARB) and genes (ARGs). Therefore, based on the noval concept of source control of ARGs in antibiotic-containing water, it is a promising way to eliminate the antibacterial activity of antibiotics by abiotic pretreatment technology before subsequent biological treatment to ensure the stability of wastewater treatment system and prevent the transmission risk of ARGs.
    Compared with hydrolysis and electro-Fenton oxidation, UV photolysis was selected as an appropriate pretreatment technology for antibiotic-containing wastewater. It could decompose many kinds of antibiotics and was not inhibited by the coexisting organics in wastewater. The antibacterial activities of five kinds of antibiotics, which were eliminated with UV irradiation, exhibited a significantly positive correlation with their parent compound concentrations. The photodecomposition of the main functional groups in antibiotics contributed to the elimination of antibacterial activity. Defluorination was the main pathway to eliminate the antibacterial activity of antibiotics containing a fluorine substituent (e.g., florfenicol and ofloxacin), while the photoinduced opening of the β-lactam ring was the most efficient route to eliminate the antibacterial activity of β-lactam antibiotics (e.g. cefalexin, amoxicillin and ampicillin). These results demonstrated that UV photolysis could be adopted as an efficient and promising pretreatment strategy for the source control of antibiotic antibacterial activity by the decomposition of antibiotic functional groups before the biological treatment unit.
    In order to verify the antibiotics without antibacterial activity will also lose the potential of inducing ARGs, a combined system for the treatment of florfenicol (FLO)-containing synthetic wastewater with different UV irradiation doses coupled with aerobic or anaerobic biological process was constructed. It was found that UV radiation pretreatment significantly diminished the diversity and abundance of detected ARGs in both aerobic and anaerobic bioreactors, especially the chloramphenicol ARGs closely related to FLO. Among them, after 2 hours or more of UV irradiation pretreatment, the relative abundance of floR in aerobic and anaerobic biological treatment decreased by two orders of magnitude, which was at the same level as the negative control group (10–3 copies/16S rRNA copies). Meanwhile, the relative abundance of floR under aerobic condition was generally higher than that under anaerobic condition, and the abundance of floR on plasmid DNA was higher than that on genomic DNA under the same condition. UV photolytic pretreatment also effectively reduced the relative abundances of intI1 on both genomic and plasmid DNA, keeping them at the level of blank control (< 1.0  10–1 copies/16S rRNA copies), which reduced the potential risk of horizontal transfer of floR. Moreover, UV irradiation pretreatment with a sufficient dose shaped the structure and composition of sludge microbial communities closer to those of the FLO-free groups. During this process, the relative abundances of Pseudomonas and Escherichia-Shigella working as the potential hosts of ARGs were significantly reduced with the increase of UV irradiation dose in aerobic and anaerobic bioreactors, respectively.
    Considering the problems of long treatment time and low efficiency in the elimination of antibacterial activity by UV photolysis pretreatment, the dechlorination and defluorination performance of FLO photolysis process were improved by adding sulfite to introduce reducing free radicals. The correlation between antibacterial activity and defluorination rate of FLO was higher than that with the corresponding dechlorination rate. After 12 min UV/sulfite (UV/S) photolytic pretreatment, the relative abundance of floR was controlled at the level of blank control group (6.52 ± 0.60  10–4 copies /16S rRNA copies), which was equivalent to that of 20 min UV photolysis pretreatment.  In addition, the conditions with excessive dissolved oxygen orpH > 8 were not conducive to the decomposition of FLO. The coexistence of humic acids above 5 mg L–1 significantly inhibited the decomposition of FLO, while other coexisting substrates (protein, glucose and HCO3–) did not affect the decomposition of target antibiotics. Moreover, the inhibitory effect of NO2– as eaq– and H• quehcher on the decomposition of FLO was significantly higher than that of NO3– as eaq– quencher at the same concentration, which indicated that there was a reductive dechlorination and defluorination process dominated by H• in UV/S photolytic system. Furthermore, UV/S system could also be used to decompose other chloramphenicols and fluoroquinolones. Compared with the UV/H2O2 and UV/peroxydisulfate systems in the same concentration of additives, the decomposition rate constant of FLO in UV/S system was the highest, and it was not affected by coexisting organic compounds.

Pages156
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/43565
Collection中国科学院环境生物技术重点实验室
Recommended Citation
GB/T 7714
丁养城. 紫外光解削减水中抗生素抗菌活性及阻控抗性基因传播研究[D]. 北京. 中国科学院生态环境研究中心,2020.
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