水稻土Fe(Ⅲ)的异化还原对磺胺类抗生素降解转化的微生物-化学作用机制

Dissimilatory Fe(Ⅲ) reduction is commonly found in soil and sediment of the biological chemical process. Antibiotics pollution is becoming a global concern. The antibiotics into the soil will simultaneously occur in a series of physical, chemical and biological reactions, which may ultimately alter their ecological toxicities. Dissimilatory Fe(Ⅲ) reduction will not only influence the iron distribution, but also result in the environmental degradation and transformation of persistent organic pollutants like antibiotics. This project focused on the effect of dissimilatory Fe(Ⅲ) reduction on the biotic and abiotic transformation of sulfonamide antibiotics in paddy soil. The research starting point is produced from the forms and activities of antibiotics in soil, the characteristics of antibiotic adsorption on iron oxides and humic substances, and iron reduction microbial response for antibiotic resistance. The study main line is performed on the mechanisms for the antibiotics with microbial degradation, and hydrolysis, oxidation reduction degradation, etc. The associated bridge is established by the change of iron reduction microbial community, the generation of Fe(Ⅱ) and other active substances, and the modification of environmental conditions due to dissimilatory Fe(Ⅲ) reduction in soil. Based on above these research results, the connections between dissimilatory Fe(Ⅲ) reduction and antibiotics transformation are constructed, and the mechanisms that dissimilatory Fe(Ⅲ) reduction mediated biotic and abiotic degradation of the antibiotics are proposed by the identification of intermediate and final products of antibiotic degradation. The research results will provide a scientific basis for the diagnosis of antibiotics pollution, the potential environmental risk assessment, and the remediation of antibiotics contaminated soil.

水稻土Fe(Ⅲ)异化还原是普遍发生的生物化学过程。抗生素污染是最受全球关注的环境问题之一，进入土壤中的抗生素将发生一系列的物理、化学和生物反应，并最终影响其生态毒性。土壤中Fe(Ⅲ)异化还原不但对铁的分布产生影响，而且对抗生素等持久性有机污染物的降解转化具有重要意义。 本项目以磺胺类抗生素污染土壤中抗生素的残留形态与活性、抗生素与铁氧化物/腐殖质的结合特征、抗生素污染土壤铁还原菌种群特性为"基础"，以抗生素在土壤中微生物降解以及水解、氧化还原降解等非生物转化的机制研究为"主线"，以土壤中铁还原的微生物、铁还原的化学活性物质、铁还原的生物-化学效应研究为"桥梁"，建立铁的微生物还原与抗生素降解转化过程之间的联系，解析抗生素降解转化的中间产物和最终产物，揭示Fe(Ⅲ)异化还原调控抗生素降解转化的微生物与化学作用机理，为土壤抗生素污染诊断、潜在环境风险评估及开展抗生素污染修复提供科学依据。

水稻土Fe(Ⅲ)异化还原是普遍发生的生物化学过程。抗生素污染是最受全球关注的环境问题之一，进入土壤中的抗生素将发生一系列的物理、化学和生物反应，并最终影响其生态毒性。土壤中Fe(Ⅲ)异化还原不但对铁的分布产生影响，而且对抗生素等持久性有机污染物的降解转化具有重要意义。. 本项目围绕铁微生物还原与土壤中抗生素降解转化过程之间关系，重点阐明Fe(Ⅲ)异化还原调控抗生素降解转化的微生物-化学作用机理。. 通过比较分析几种典型铁氧化物对磺胺类抗生素的吸附与氧化降解性能，提出铁氧化物催化类Fenton反应降解磺胺类抗生素的途径，研发制备的铁锰二元氧化物比单一铁氧化物具有更好的催化氧化能力，使用过氧化钙（CaO2）替代传统的过氧化氢（H2O2）催化类Fenton反应更容易使磺胺抗生素发生降解。. 研究了两种代表性铁还原菌Shewanella oneidensis MR-1和Shewanella sp. strain MR-4 对磺胺类抗生素的耐药性与降解特性，研究发现铁还原菌对磺胺类抗生素有较强的耐药性，同时铁还原菌对磺胺类抗生素有一定的降解能力，通过降解产物分析推测磺胺类抗生素的生物降解途径可能由S-N键断裂引起。. 考察了铁异化还原过程和电子穿梭物质对铁还原菌降解磺胺类抗生素的影响，研究发现异化Fe(Ⅲ)还原对磺胺类抗生素的生物降解有显著促进作用，外源添加腐殖质能够显著提高铁还原菌对磺胺类抗生素的降解效率，并从化学与生物角度探讨蒽醌-2,6-二磺酸盐（AQDS）和核黄素等电子穿梭物质对S. oneidensis MR-1降解磺胺甲恶唑及铁还原的影响，揭示电子穿梭物质对铁还原菌降解磺胺类抗生素的强化机理。. 研究结果可为自然环境中铁的微生物还原介导土壤中抗生素的生物和非生物转化提供科学依据，对控制和消除土壤中抗生素污染具有重要的指导意义，并为受到抗生素污染土壤修复提供理论依据和技术支撑。