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.