抗生素对河口近岸反硝化过程的影响及其微生物作用机理

Denitrification is the dominant pathway of nitrogen removal in estuarine and coastal ecosystems, and plays a significant role in counteracting aquatic eutrophication induced by excessive nitrogen loads. Estuarine and coastal environments also suffer from increasing antibiotic residue due to the growing production and usage of antibiotics. However, little is known about the mechanisms of how antibiotics influence on denitrification. In this study, the Yangtze Estuary is selected as the study area, and we intend to conduct sediment slurry incubation experiments combined with 15N isotope-tracing technique in order to determine how antibiotics influence on denitrification rates and N2O release rates. Quantification of denitrification gene and antibiotic resistance gene were also conducted to investigate the microbial physiological mechanisms underlying the antibiotics effect on denitrification. The main purpose of this study is to reveal the potential influence of residual antibiotics on denitrification and the physiological response of denitrifying bacteria to the presence of antibiotics at the gene level. This study can also provide primary data for the control of reactive nitrogen and antibiotics pollution along with a further understanding of the mechanisms of antibiotics residue influence on denitrification.

反硝化过程是河口近岸环境中最为主要的活性氮去除途径，对于缓解水体富营养化具有重要的作用。近年来由于抗生素的大量生产和使用，抗生素在河口近岸环境中呈现高浓度残留。然而，目前就抗生素对河口近岸反硝化过程的影响及其作用机理尚缺乏深入系统的研究和探讨。鉴于此，本项目拟选取长江口近岸作为典型研究区，采用稳定氮同位素示踪与分子生物学技术手段，研究河口近岸抗生素残留对反硝化过程及其中间产物氧化亚氮释放的影响，分析反硝化细菌群落多样性、反硝化功能基因和抗性基因对抗生素的响应特征，以揭示抗生素对河口近岸反硝化及氧化亚氮产生的微生物调控机理。通过本项目研究，不仅可以深化河口近岸环境中抗生素残留对反硝化过程影响机制的理论认识，同时可为河口近岸抗生素和氮素污染的防治提供重要的科学依据。

反硝化过程是河口近岸生态系统中最主要的硝态氮削减途径，同时也是N2O释放的重要来源。因为人类生活和生产的大量使用，抗生素的持久性暴露也造成了河口近岸区域的一系列环境问题。在河口近岸生态系统中，抗生素暴露对反硝化过程的影响模式和微生物作用机理目前尚不清楚。因此，开展河口近岸区域内抗生素对反硝化过程的影响研究，是当今自然地理学、环境科学等相关研究领域内新兴的热点科学问题。本项目以长江口潮滩作为典型研究区，研究了河口近岸沉积物中抗生素的动力学变化特征，阐明了抗生素单一暴露及复合暴露对河口近岸沉积物中反硝化速率和N2O释放速率的影响模式，揭示了抗生素对河口近岸沉积物反硝化过程影响的微生物作用机理。相关研究成果已在《Journal of Geophysical Research》、《Applied Microbiology and Biotechnology》、《Environmental Pollution》、《Chemosphere》、《Scientific Reports》等国际重要学术期刊上发表学术论文8篇，另获批发明专利一项。上述研究成果揭示了河口潮滩中抗生素污染物对反硝化过程的影响机制，深化了河口近岸区域新型有机污染物和氮循环过程的理论认识，为河口近岸区域抗生素污染和氮素污染的治理提供了数据支持和理论依据。