DNA has been modified to make it store data 350 times faster

DNA has been used for years to store data, but encoding information into the molecule is painstaking work. Now, researchers have drastically sped it up by mimicking a natural biological process that drives gene expression. This could lead to durable, do-it-yourself DNA data storage technologies.

Even though a single gram of DNA can store hundreds of millions of gigabytes of data, the technology to make use of this isn’t yet fully viable. This is partly because the process of encoding data in DNA requires that each molecule be synthesised “from scratch” after being designed to encode a specific piece of information.

Long Qian at Peking University in China and her colleagues have now developed a way to write information onto DNA more efficiently.

“A good analogy is using a typewriter, where you have to type each letter, versus printing,” says Harris Wang at Columbia University in New York, who wasn’t involved with the work. “They could essentially get all of [the information] onto the ‘paper’ all at once.”

The team turned long strands of DNA into binary code, the sequence of 1s and 0s that is used in computing to store data. They started with prefabricated DNA templates that served as a base onto which they added shorter DNA strands, similar to threading beads onto a string. Then they used a chemical reaction to add a methyl group, which is a molecule made from carbon and hydrogen, to some of these “beads”. The methylated beads become the 1s of binary code and the unmethylated ones serve as the 0s.

Cells naturally use the same methylation process to “modify DNA without changing the underlying sequence, allowing them to store additional layers of regulatory information stably over time”, says Qian. She and her colleagues worked out how to perform this process many times at once, in parallel, by adding a special bar code to each template. This let them write 350 units of information, or bits, onto a DNA sample at once – hundreds of times more than the previous standard of just one bit at a time.

In tests, they stored an image of a panda and of a rubbing in the shape of a tiger from ancient China, then retrieved them with a DNA sequencer aided by an error correcting algorithm. The retrieved images were reproduced with 97 per cent accuracy or more.

Finally, they made the process so convenient that 60 student volunteers could practise storing text in DNA samples using do-it-yourself kits that included simple chemistry equipment for the methylation reaction and a computer program that translated their words into code. Though these volunteers hadn’t been previously trained to work with DNA, the error rates in their encoding process were smaller than 2 per cent. Qian says this could lead to “desktop DNA printers or storage kits [that] could be developed for use at home or in small organisations, enabling users to back up important personal data, such as legal documents or digital photos, in a form that can last for centuries”.

Wang says DNA-based technology could be especially useful for archival storage, and while technology discs and magnetic tape may eventually fall by the wayside, he thinks that DNA sequencing will only keep getting better.