Humans have an uneasy relationship with bacteria- they can make us very sick, but we also couldn’t live without the complex society residing in our guts. Now, researchers at Rice University have engineered E.coli to help detect inflammation in the colon of mice by infiltrating that microbiome and sending color signals through their feces. Eventually this could lead to self-diagnosis tests for humans and if your poop turns out blue, you should probably see a doctor.
Since the human gut is home for a variety of microorganisms, in some cases, the tools don’t exist to reliably diagnose conditions, so bacteria engineered to react to certain biomarkers could help in that role.
“The gut harbors trillions of microorganisms that play key roles in health and disease,” says Jeffrey Tabor, lead author of the study. “However, it is a dark and relatively inaccessible place, and few technologies have been developed to study these processes in detail. On the other hand, bacteria have evolved tens of thousands of genetically encoded sensors, many of which sense gut-linked molecules. Thus, genetically engineered sensor bacteria have tremendous potential for studying gut pathways and diagnosing gut diseases.”
The Study:
The Rice team focused on detecting Colitis– An inflammatory condition of the colon. Previous studies had shown that elevated levels of thiosulfate might be a biomarker for the condition, Hence Researchers engineered E. Coli that could sense thiosulfate and respond by producing proteins that fluoresced green.
The trial group consisted of 1. Healthy mice and 2.A group of mice that suffered from colitis.
They were given billions of the bacteria and as expected the feces of the mice with colitis glowed green when viewed under flow cytometer- indicating elevated levels of thiosulfate and thereby the presence of Colitis. The more inflamed the mouse’s colon was, the brighter their poop glowed.
More research is required for deriving a biomarker for colitis in humans, however the general principle of using engineered bacteria to sense and fluoresce as a diagnosis could carry across. Researchers say, a system could be developed where bacteria express a colored pigment that could be spotted with lab equipment allowing amateur diagnosis of certain conditions at home.
“We’d like to develop a home inflammation test where a person prone to colitis flare-ups would eat yogurt that contained the engineered bacteria and see blue pigment in the toilet if they were sick,” says Tabor.