Glowing Bacteria

Escherichia coli, more commonly known as E. coli, are a normal part of the human digestive tract. Certain strains, however, are among the most deadly bacteria associated with food poisoning.

While part of medical research is focused on slowing these types of bacteria, other studies are focusing on how to change the wiring of these bugs to help in the diagnosis of diseases.

Synthetic Bacteria

Two new studies released Wednesday in the journal Science suggest that rewriting E. coli’s circuitry may aid in the early diagnosis of cancer as well as detecting abnormal blood sugar levels in people with diabetes.

These two findings are part of a field of medicine known as synthetic biology, which combines several areas of study to design biological devices with specific functions. These functions can include producing or delivering drugs as well as detecting disease in the body or toxins in the environment.

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Bacteria Glows at Early Signs of Metastatic Cancer

Liver transplants are one surgical option for people with liver cancer, but long waiting periods for a donor are common. As of early Wednesday, there were 15,241 candidates awaiting a donated liver in the United States, according to the Organ Procurement and Transplantation Network.

Liver metastasis, or cancer that has spread to the liver from another organ, is treatable, but it is often detected too late.

Earlier diagnosis could help reduce the number of people awaiting donor organs and help save lives.

Synthetic biologist Tal Danino, a postdoctoral fellow at the Massachusetts Institute of Technology, researches the use of bacteria for cancer diagnostics and therapy. He and his team say they’ve programmed bacteria to glow when it detects cancer cells in the liver.

To find those cells, all it takes is a basic urine sample.

Bacteria are known to have an affinity for tumors, so researchers engineered E. coli to produce an enzyme in the presence of cancer cells. This enzyme is then detected in the liver.

To test this, researchers fed the altered bacteria to mice bred to have liver metastases from several organs, including the colon, lung, ovaries, and pancreas.

The bacteria colonized around tumors. The excreted enzyme broke down a compound that makes molecules light up when excreted in urine. The bacteria were able to alert researchers to the cancer cells in the liver within 24 hours.

Researchers say these enzyme-producing bacteria have other cancer-detecting applications, including spotting tumors in the gastrointestinal tract.

While the mice showed no serious side effects for up to a year, further testing is needed.

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Bacteria May Be Able to Help Diagnose Diabetes

When your body doesn’t process sugars properly, the excess is also excreted through urine. This puts excess strain on your kidneys and causes frequent urination.

Abnormally high blood glucose levels can be detected by using a disposable dipstick.

Synthetic biologist Alexis Courbet and colleagues at the Centre National de la Recherche Scientifique in Montpellier, France, report they’ve been able to engineer E. coli to detect high glucose levels almost as well as the dipsticks being used today.

The rewired bacteria are designed to change color at a certain threshold of glucose. The cells are suspended in hydrogel balls for easy handling and read-out.

Researchers say this method accurately and reliably detected abnormal glucose levels in urine samples from diabetic patients. 

Researchers say their experiments offer a glimpse into how these repurposed bacteria may be adopted for noninvasive cancer detection applications for home use or in the field where advanced cancer diagnostics aren’t available. 

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