Sulfonamide-metabolizing microorganisms and mechanisms in antibiotic-contaminated wetland sediments revealed by stable isotope probing and metagenomics
Sulfonamide-metabolizing microorganisms and mechanisms in antibiotic-contaminated wetland sediments revealed by stable isotope probing and metagenomics
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DOI：
10.1016/j.envint.2022.107332
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发表时间：
2022-06-07
影响因子：
11.8
通讯作者：
Xie, Shuguang
中科院分区：
文献类型：
--
作者：
Chen, Jianfei;Yang, Yuyin;Xie, Shuguang
磺胺类抗生素是畜禽养殖和水产养殖废水中普遍存在的污染物，它增加了抗生素抗性基因的繁殖。具有降解SA能力的微生物在SA的消散中起着重要作用，但其多样性和降解机制尚不清楚。本研究采用DNA稳定同位素探针技术（SIP）结合宏基因组学技术，对受重金属污染的湿地沉积物中SA的活性微生物及其生物降解机制进行了研究。DNA-SIP揭示了各种SA同化细菌占主导地位的变形菌门的成员，如慢生根瘤菌，芽单胞菌，和未分类的伯克霍尔德氏菌科。磺胺嘧啶和磺胺甲恶唑主要通过最初的异羟化作用消散，并由类似的微生物驱动。sadA基因编码一个依赖于NADH的单加氧酶，在13 C重链DNA中富集，证实了其对沉积物中SA初始异羟化的催化能力。此外，基于宏基因组学分析，还发现一些双加氧酶基因参与了SA的羟基化和芳环裂解，可能在变形菌为优势活性菌的沉积物生态系统中SA代谢中发挥重要作用。我们的工作阐明了未培养的微生物在其自然栖息地的生态作用，并提供了一个更深入的了解原位SA生物降解机制。
Sulfonamide (SA) antibiotics are ubiquitous pollutants in livestock breeding and aquaculture wastewaters, which increases the propagation of antibiotic resistance genes. Microbes with the ability to degrade SA play important roles in SA dissipation, but their diversity and the degradation mechanism in the field remain unclear. In the present study, we employed DNA-stable isotope probing (SIP) combined with metagenomics to explore the active microorganisms and mechanisms of SA biodegradation in antibiotic-contaminated wetland sediments. DNA-SIP revealed various SA-assimilating bacteria dominated by members of Proteobacteria, such as Bradyrhizobium, Gemmatimonas, and unclassified Burkholderiaceae. Both sulfadiazine and sulfamethoxazole were dissipated mainly through the initial ipso-hydroxylation, and were driven by similar microbes. sadA gene, which encodes an NADH-dependent monooxygenase, was enriched in the 13C heavy DNA, confirming its catalytic capacity for the initial ipso-hydroxylation of SA in sediments. In addition, some genes encoding dioxygenases were also proposed to participate in SA hydroxylation and aromatic ring cleavage based on metagenomics analysis, which might play an important role in SA metabolism in the sediment ecosystem when Proteobacteria was the dominant active bacteria. Our work elucidates the ecological roles of uncultured microorganisms in their natural habitats and gives a deeper understanding of in-situ SA biodegradation mechanisms.