珠三角鱼鸭混养塘中AmpCβ-内酰胺酶基因的迁移行为及相关机理研究

Cephalosporins resistance genes are most important antibiotics resistance genes for ecological safety and humanic healthy, because Cephalosporins are widely used front-line antibiotics in human clinical practice, and their consumption and extra-label use in farming practices is a common phenomenon. It is pity that the detail transfer pathway and mechanism of Cephalosporins resistance genes is nearly unknown so far, and worth further research. We have studied the distribution of Cephalosporins resistance genes in many fish-duck complex ponds of the Pearl River Delta and found an obvious positive relationship between AmpC β-lactamase genes and heavy metals. Therefore, the simulation and case study will be conduted to complement each other. The change of bacterial community, host bacteria classification and AmpC β-lactamase genes, as well as the relationship among water quality, ARGs and pathogen, will be determined by the HTS-based metagenomic approach and analyzed by bioinformatics. Moreover, a combined technique of labeling gene tracer and transconjugant will be used to study the HGT potential of AmpC β-lactamase genes and its trigger conditions. The transfer characteristics and mechanisms of AmpC β-lactamase genes will be drawn by statistics and modeling calculation, which will provide scientific basis and theoretical foundation for further study on the pathway behavior of AmpC β-lactamase genes in the outside of farms.

头孢菌素是目前人类医疗的一线抗生素，不仅用量大，而且“人药兽用”现象普遍，因此，头孢菌素抗性基因是对生态安全和人类健康危害最大的一类抗生素抗性基因（ARGs），其在环境中的详细环境行为及机理仍不清楚，值得研究。课题组前期研究发现珠三角鱼鸭混养塘中AmpC β-内酰胺酶基因分布广、浓度较高，且与重金属之间存在明显正相关性。因此，本项目拟综合实例和模拟研究，从水质条件（Cu/Zn、pH、头孢菌素）出发，利用宏基因组测序和生物信息学，研究菌群结构、AmpC β-内酰胺酶基因丰度及宿主多样性的变化，功能ARGs和致病菌之间的关系；利用荧光标记示踪和转化接合子组合技术研究AmpC β-内酰胺酶基因的水平迁移能力，筛选HGT诱发条件；最后通过分析统计和建模计算，总结AmpC β-内酰胺酶基因的迁移特性及相关机理，为进一步解释该基因污染物进入外环境的环境行为和健康风险奠定基础。

鱼鸭混养塘中广泛存在AmpC β-内酰胺酶抗性基因及重金属抗性基因，本研究综合实例和模拟研究，从水质条件（Cu/Zn、pH、头孢菌素）分析出发，利用宏基因组测序和生物信息学等方法与技术，对AmpC β-内酰胺酶抗性基因丰度及其相关菌群多样性进行了研究。通过荧光标记示踪和转化接合子组合技术，追踪了AmpC β-内酰胺酶抗性基因的水平迁移能力。研究发现：混合养殖体系比单一养殖体系更容易诱导抗性基因产生，且AmpC β-内酰胺酶抗性基因在环境及生物体中发生迁移的频率更高，环境胁迫因子还会促进抗性基因从水体向生物膜及肠道发生迁移，且养殖体系中的AmpC β-内酰胺酶类抗性基因比重金属抗性基因更容易迁移。本项目研究所形成的AmpC β-内酰胺酶抗性基因发生迁移特性及相关机理，为外源抗性基因污染的环境行为及健康风险提供了重要工作基础和启示性线索。项目资助发表学术研究论文10篇，其中SCI 8篇，中文核心2篇。培养硕士研究生8名，其中5名已经取得硕士学位，3名在读。项目投入经费650000. 00元，支出637546. 38元，各项支出基本与预算相符。剩余经费12453. 62元，剩余经费计划用于本项目研究后续支出。