基于合成生物学手段的益生菌定向改造用于镉暴露的选择性生物减除和预警的探索研究

镉作为非必需元素可对人体健康造成严重危害，环境污染导致的膳食镉暴露是人体镉摄入的首位因素。近年来围绕阻断镉消化道吸收新策略的探索一直未有所突破。已有研究表明耐镉益生菌可用于体镉的生物减除，但其对金属离子的吸附缺乏选择性，这也是传统膳食疗法难以克服的缺点。项目组近年来在微生物重金属抗性调控系统的定向改造方面积累了一定研究基础。本项目以2种天然来源的镉抗性操纵子为设计蓝本，通过合成生物学手段构建一系列人工操纵模块，拟将益生菌定向改造为选择性响应镉的全细胞吸附-传感器，达到高选择性镉吸附肽的益生菌细胞表面展示和不同浓度范围镉暴露的双荧光报告差异指示的目的。进一步通过细胞、肠道芯片及动物模型，拟实现工程菌在宿主肠道黏膜定殖过程中选择性富集镉阻断其吸收和镉肠道暴露的活体荧光预警，为基于益生菌全细胞生物吸附及传感技术来实现宿主肠道重金属暴露的选择性驱除及生物预警提供概念验证。

Cadmium, as a non-essential element, can cause serious harm to human health. Dietary cadmium exposure caused by environmental pollution is the first key factor responsible for human cadmium intake. In recent years, there has been no breakthrough in the development of novel strategies to block the absorption of cadmium in the digestive tract. Although previous studies have shown that cadmium tolerant probiotics can be used for biological removal of cadmium in vivo, their adsorption towards cadmium is not specific. It is also an insurmountable problem in traditional dietary therapy. The directional transformation of microbial heavy metal resistance regulation system has always been the study focus of the project team. Based on two natural cadmium resistant regulation systems from microbial origin, a series of artificial cad regulation modules will be constructed using synthetic biological approaches in this project. The probiotics are going to be transformed into a whole cell adsorber and biosensor specific to cadmium. Surface display of cadmium adsorption peptide, and double fluorescent reporters for cadmium in different concentration range can be achieved in engineered probiotics. The application potential of engineered probiotics in cadmium adsorption and fluorescence indication during host intestinal mucosa colonization will be studied through cell model, intestinal chip, and animal model. This project will provide proof-in-concept for the selective elimination of host intestinal heavy metal exposure and biological warning based on probiotic whole cell biosorption and biosensing approaches.