反硝化作用与槐糖脂协同强化土壤抗生素-抗性基因厌氧消减的耦合机制

Unregulated application of veterinary antibiotics in animal husbandry industry has resulted in fairly amount of antibiotic/antibiotic resistant genes (ARGs) mixed contaminated farmland soils in China, which has also caused potential threaten against human health and ecological safety. Therefore, it has been becoming a necessity to carry out targeted remediation. So far, antibiotic degradation in aerobic soils has been systematically carried out by previous researchers. Degradation research in anaerobic, though equally important, which were much less studied due to more complex impacting factors, such as oxygen deficiency, and ariance in reduction systems, electron acceptors, antibiotic classification and bioaccessibility. In this proposal, an anaerobic system (nitrate reduction system) will be designed to study the role of factors including nitrate reducing strength (nitrate concentation) and antibiotic bioaccessibility (sophorolipid addition) in prompting the anaerobic dissipation of soil antibiotics and ARGs. Moreoever, the Surface Response Model, a Three Compartment Desorption Model, 13C stable isotope method, and high throughput sequencing technology will be employed to explore the main factors that limit the dissipation of mixed pollutants; illucinate the microbial ecological response mechanism of antibiotic degradating bacteria, antibiotic resistant bacteria, and denitrifiers. The study will provide theoretical direction and scienfitic bases for better understanding the sophorolipid-enhanced soil antibiotic/ARGs dissipation in denitrifying condition.

兽药的滥用导致了在我国许多畜禽养殖场周边出现了大面积抗生素-抗性基因(antibiotic resistant genes, ARGs)复合污染农田土壤，给人体健康和生态环境安全带了较严重隐患，开展针对性修复研究十分必要。国内外学者对好氧条件下土壤抗生素降解已有较为系统研究，但在厌氧环境中，由于受到氧气、还原反应体系、电子受体和微生物活性等因素限制，抗生素-ARGs消减研究进展缓慢。本项目拟在纯厌氧环境中，硝酸盐还原体系下，从调节电子受体浓度(硝态氮添加量)和促进抗生素微生物可利用性(生物表面活性剂槐糖脂添加量)的角度，探究反硝化强度与槐糖脂对土壤抗生素-ARGs同步厌氧消减的交互作用，探明决定消减进程的关键因素，阐释消减过程中抗生素厌氧降解菌群、抗性细菌菌群及反硝化细菌菌群在群落生态功能上的响应机制，为反硝化作用与槐糖脂协同强化土壤抗生素-ARGs厌氧消减修复提供理论指导和科学依据。

兽药的滥用导致了在我国许多畜禽养殖场周边出现了大面积抗生素-抗性基因(antibiotic resistant genes, ARGs)复合污染农田土壤，给人体健康和生态环境安全带了较严重隐患，开展针对性修复研究十分必要。微生物强化降解是一种环境友好、经济高效的土壤修复技术。.（1）本项目通过采集典型畜禽粪便周边土壤，发现三角3处畜禽养殖场周边土壤及3处蚓粪厂调查结果显示畜禽粪便农用土壤及不同粪便来源的蚓粪样品中均有抗生素检出，主要类型为四环素、磺胺嘧啶、罗红霉素，污染较严重，具有较广泛代表性；.（2）土壤微域培养试验研究添加硝态氮和槐糖脂对土壤中抗生素及抗性基因消减的影响。研究发现土壤中添加0.1%（w/w）槐糖脂，有助于加速硝态氮的消减速率和进程，反硝化作用过程的强度显著增强。单独或同时添加槐糖脂或硝态氮均对抗生素及ARGs丰度消减具有显著效果（p<0.01）；同时添加槐糖脂和硝态氮对总量抗生素最大去除量约为57%，对于胞外eARG降低效果可达到102-103拷贝数/克。.（3）针对当前抗生素耐药菌复合污染土壤的环境问题, 本研究进一步提出了基于噬菌体疗法靶向灭活土壤中多种抗生素耐药菌的修复技术。研究分离筛选出2株多价噬菌体YSZ1R和YSZ5K在同步灭活粪肠杆菌和假单胞菌属细菌的能力显著高于专一型噬菌体的相应灭活能力, 同时使用多价噬菌体疗法也有助于维护和改善修复后土壤微生物生态功能多样性与稳定性。.本项目从调节电子受体浓度(硝态氮添加量)和促进抗生素微生物可利用性(生物表面活性剂槐糖脂添加量)的角度，探究反硝化强度与槐糖脂对土壤抗生素-ARGs同步厌氧消减的交互作用，探明决定消减进程的关键因素；并进一步采用温室盆栽试验，研究槐糖脂对土壤-生菜体系中抗生素及胞内外抗性基因的影响，阐明土壤及生菜微生物群落的响应机制，为槐糖脂及噬菌体强化土壤及农作物中抗生素、抗性基因及抗生素耐药菌的强化消减修复提供理论指导和科学依据。