By Robert F. Service
Hard drives and optical drives store GB of digital data with the push of a button. But these technologies — like the magnetic tapes and the floppy drives in front of them — are likely to become outdated and unreadable when the new technology bypasses them. Now, researchers have come up with a way to electronically write data into the DNA of live bacteria, a storage option that is unlikely to become obsolete anytime soon.
«This is a really cool move,» says Seth Shipman, a bioengineer at Gladstone Institutes and the University of California, San Francisco, who was not involved in the new work. «This is a really cool move» that could one day spur commercial development. However, he notes that real-world applications are still a long way off.
DNA is attractive for storing data for several reasons. First, it’s 1,000 times more dense than compact hard drives, which allows them to store the equivalent of 10 full-length digital movies the size of a grain of salt. Because DNA is such an essential component of biology, the techniques for reading and writing it are expected to become cheaper and more powerful over time.
Storing data in DNA is not a new idea. To do this, researchers typically convert the series of numeric data files and zeros into groups of the four bases of the molecule: adenine, guanine, cytosine, and thymine. Then they use the DNA complex to write that code in DNA. But the accuracy of DNA synthesis decreases the longer the code lasts, so researchers typically split their files into chunks and write them into snippets of DNA between 200 and 300 bases in length. Each snippet is given an index to locate it in the file, and then the DNA sequences read the snippets to reassemble the file. But the technology is expensive, as it costs $ 3,500 to collect 1 megabit of information. The DNA flasks in which the information is stored can degrade over time.
To create a long-term, easier-to-encode medium, researchers are now working to write data into the organisms’ DNA, which copies the genes and transmits them to the next generation. In 2017, a team led by Harris Wang, a systems biologist at Columbia University, used a gene-editing CRISPR system to recognize a biological signal, such as the presence of fructose. When researchers added fructose to Coli Cells, gene expression increased in ring-shaped parts of DNA called plasmids.
Then, components of CRISPR — which had evolved to defend bacteria from virus invaders — cut the overexpressed plasmid into pieces and lodged some of it in a particular section of the bacterium’s DNA that «remembered» the previous viral invaders. The input gene bit represents a digital one. If the fructose signal is absent, the bacteria instead store a random portion of their DNA, which is numerically zero. sequence Coli Then DNA revealed that the bacteria were exposed to either one or zero fructose.
But because this setup can only store a few bits of data, Wang and colleagues have replaced the fructose recognition system with a system that can encode longer strings of information: electronic input. They insert a series of genes into Coli That enabled cells to increase plasmid expression in response to an electrical voltage. As with the fructose preparation, the increase in expression resulted in the digital component being stored in the bacterial DNA. To read the ones and zeros, the researchers simply arranged the bacteria.
Using this approach, Wang and colleagues performed electrical coding Up to 72 bits of data, To write the message «Hello world!» They report today at Biology of Chemical Nature. They also showed that they can add up Coli By message them to a mix of regular soil microbes — then sequence the mixes later to recover their stored message.
Wang says that storing data in living organisms is still early. «We will not compete with current memory storage systems,» he says. Researchers will also need to find ways to prevent their messages from deteriorating as the bacteria mutate as they reproduce. But for now at least, it might give James Bond a new tool to hide messages in sight.