Silicon-based memory storage is reaching an impasse. Like batteries, the technology hasn’t evolved very much over the last few decades, apart from getting smaller and more powerful, and there’s only so small we can get before the devices will stop working.
With this in mind, researchers around the world have recently demonstrated that the future of memory may be in biology, not technology. Just this year, one team demonstrated how the whole of human history could be stored on a drop of DNA. Now, as revealed in a new paper in Science, colonies of bacteria have been converted into information-storing critters – or, to put it another way, biological hard drives.
Before this point, the most that any researcher had managed to splice into a living cell was 11 bits of information – roughly the storage space required for two alphanumeric characters. This new technique is able to encode roughly 100 bytes of data, a 73-fold increase in storage capacity. This is approximately the storage space required to digitally encode the sentence you’re reading right this very moment.
Is this the future of memory storage? anyaivanova/Shutterstock
“Rather than synthesizing DNA and cutting it into a living cell, we wanted to know if we could use nature's own methods to write directly onto the genome of a bacterial cell,” Seth Shipman, a Harvard University geneticist, told Popular Mechanics.
This way, if the bacterium replicated as it normally would, the information would be copied down through the generation. When this data is stored in a hard drive that could theoretically keep increasing in size over time, scientists could read it by examining its genome any time they wished, using any of the bacteria in the colony.
In the DNA storage study, scientists essentially added the information in the form of code to a genetic sequence, but this study chose a different path with different tools. Specifically, the revolutionary gene-editing technique known as CRISPR was employed.
CRISPR is a natural defense system employed by bacteria in order to defend themselves against bacteriophages, viruses that specifically infect bacterial cells. Using enzymes, certain bacteria are able to snip out parts of the attacked virus’ DNA – or, as recently discovered, their RNA. This not only weakens the attack, but the removed DNA chunk allows the bacteria to remember how this virus behaves just in case it attacks again.
This stolen viral genome chunk is then copied as the bacterium replicates, meaning that the viral defense is passed through the new generations of bacteria. The team of researchers realized that if they introduced a viral-like piece of genetic information to a colony of CRISPR-enabled bacteria – in this case, E. coli – they would cut it to pieces and make it part of themselves.
A render of a CRISPR modification complex from a bacterial cell. molekuul_be/Shutterstock
Thankfully, these bacteria store their new snipped DNA chunks sequentially, so it’s very clear which order they attacked which viral strain. So instead of the viral DNA (or in this case the fake viral DNA) being stored in a random order, each new bit of genetic information is “stacked” in chronological order. This means that the researchers could feed the bacteria information in a certain order and know that it would be stored and ultimately replicated in the same order, making it easy to read later down the road.
Indeed, feeding the bacteria just a few arbitrary strings of words encoded into faux-viral DNA worked fantastically, but there was one slight issue: Not all of the bacteria spliced their targets, meaning that some missed parts of the incoming data. However, between many millions of bacteria, any missing words in one group of cells showed up sequentially in other groups, meaning putting the code together wasn’t problematic.