炎症性肠病生物检测器的构建与调试

Construction and characterization of a bio-detector for inflammatory bowel disease

摘要:

利用工程改造过的肠道微生物进行无创、便宜便捷的肠道炎症检测、治疗可有效应用于医药行业。肠道炎症通常伴随着肠道中硫代硫酸盐和连四硫酸盐的增加，双组分系统ThsSR和TtrSR是两套分别检测这两种小分子的生物感受器系统。采用荧光蛋白作为指示剂需要复杂的测试仪器，不适用于家用检测环境，而肉眼可见的色素蛋白和有色小分子作为指示剂将可能扩大ThsSR和TtrSR的应用前景。两套系统分别被转入大肠杆菌Escherichia coli Top10和益生菌E. coli Nissle 1917中，sfGFP信号表达效果证明了这两套系统可用。考虑实际应用，sfGFP被一系列色素蛋白和显色小分子替换，在E. coli Top10中，一系列色素蛋白和紫色杆菌素前体protoviolaceinic acid的显色效果明显，表明了该系统具有用于实际肠道炎症检测的可行性。结果表明，改进后的ThsSR和TtrSR系统能够针对不同浓度的肠道炎症标记物作出相应程度的反应，具备用于家庭环境人体肠道炎症检测的潜力。

Abstract:

Genetically engineered intestinal microbes could be powerful tools to detect and treat intestine inflammation due to their non-invasive character, low costs, and convenience. Intestinal inflammation is usually detected along with an increasing concentration of thiosulfate and tetrathionate molecules in the intestines. ThsSR and TtrSR are two-component biosensors to detect the presence of thiosulfate and tetrathionate molecules, respectively. In real-life intestinal inflammation detection, sophisticated instruments are needed if using fluorescent proteins as reporters. However, chromoproteins and other colored small molecules, which can be seen by the unaided eye, could extend the use of ThsSR and TtrSR biosensors to detect intestine inflammation. The feasibility of ThsSR and TtrSR systems was tested by monitoring the fluorescence intensity of sfGFP in response to the concentration of thiosulfate and tetrathionate, followed by the incorporation of the two systems into Escherichia coli Top10 and E. coli Nissle 1917. The potential for the real-life application of the two systems was further corroborated by substituting sfGFP with a series of chromoproteins and a protoviolaceinic acid synthesis cassette as reporter genes. The results indicated that signal expression of the new systems had a positive correlation with the concentration of tetrathionate and thiosulfate molecules. Thus, the modified ThsSR and TtrSR system may potentially be applied in the human body for the detection of intestinal inflammation.