Microbes-laboratory assistants
Bacteria have been taught to diagnose
Polit.<url> based on AAAS News: Engineered bacteria detect cancer and diabetes in urine
Two groups of biologists this week received genetically modified bacteria that have become able to detect the presence of cancer in mice and diabetes in humans.
Sangeeta Bhatia from the Massachusetts Institute of Technology and her colleagues have previously developed a method for detecting cancer using nanoparticles. In the presence of a tumor, the nanoparticles isolated peptides, which could then be detected in the patient's urine. However, as the scientists recognized, the peptide trace turned out to be too weak to serve as a clear indicator of the disease. Then they decided to resort to the help of bacteria. To do this, a group from MIT teamed up with a team of bioengineers from the University of California at San Diego, led by Jeff Hasty. They counted on the tendency of bacteria to penetrate into tumors, since the rapidly growing tumor tissue is richly supplied with nutrients.
The researchers used Escherichia coli bacteria, whose genome was modified so that when they met with a liver tumor, the lacZ gene, which produces a certain enzyme, began to work in bacteria. Then the mice were injected with substances – precursors of luciferin, which causes luminescence. In the presence of the enzyme, the substances turned into a luminescent compound, which was then excreted from the mouse's body with urine, giving it a red color. As noted by Sangita Bhatia and her co-authors in an article published by the journal Science Translational Medicine (Danino et al., Programmable probiotics for detection of cancer in urine), if other methods struggle to detect liver tumors smaller than one square centimeter, genetically modified bacteria can diagnose a tumor of one square millimeter.
Another study was also published in Science Translational Medicine (Courbet et al., Detection of pathological biomarkers in human clinical samples via amplifying genetic switches and logic gates). A group led by biochemist Jerome Bonnet from the University of Montpellier, using a similar technique, learned to identify a key sign of diabetes, namely an increased glucose level in the patient's urine. Scientists have changed the genome of bacteria so that they produce large amounts of red fluorescent protein when the glucose content exceeds a certain level. In this case, E. coli do not even need to be injected into the body of patients, they are simply added to urine samples. This method is no more accurate than the usual method of measuring glucose. But the applied strategy can be further used to detect other substances in more complex diagnostic tasks.
Detailed popular retellings of these works are published on MIT websites (Diagnosing cancer with help from bacteria)
and Inserm (Intelligent bacteria for detecting disease) – VM.
Portal "Eternal youth" http://vechnayamolodost.ru29.05.2015