World's smallest tape recorder is built from microbes

Through a few clever molecular hacks, researchers at Columbia University Medical Center have converted a natural bacterial immune system into a microscopic data recorder, laying the groundwork for a new class of technologies that use bacterial cells for everything from disease diagnosis to environmental monitoring. 

The researchers modified an ordinary laboratory strain of the ubiquitous human gut microbe Escherichia coli, enabling the bacteria to not only record their interactions with the environment but also time-stamp the events.

"Such bacteria, swallowed by a patient, might be able to record the changes they experience through the whole digestive tract, yielding an unprecedented view of previously inaccessible phenomena," says Harris Wang, assistant professor in the Department of Pathology and Cell Biology and Systems Biology at CUMC and senior author on the new work, described in today's issue of Science. Other applications could include environmental sensing and basic studies in ecology and microbiology, where bacteria could monitor otherwise invisible changes without disrupting their surroundings.

Wang and members of his laboratory created the microscopic data recorder by taking advantage of CRISPR-Cas, an immune system in many species of bacteria. CRISPR-Cas copies snippets of DNA from invading viruses so that subsequent generations of bacteria can repel these pathogens more effectively.

"The CRISPR-Cas system is a natural biological memory device," says Wang. "From an engineering perspective that's actually quite nice, because it's already a system that has been honed through evolution to be really great at storing information."