Researchers Rewrite Massive Sections Of Bacteria's Genome


The E.coli have been radically altered. Juan Gaertner/Shutterstock

Synthetic biology has been gaining massive amounts of ground recently, as technology has been allowing biologists to alter DNA in ways unthinkable even five years ago. Now researchers have announced one of the most extensive reengineering yet of an organism's DNA. Published in Science, the study describes how a team from Harvard Medical School has managed to replace 60,000 regions of DNA in E.coli bacteria.

Put simply, the genetic code in all organisms’ codes for single amino acids in sections known as codons, and the amino acids then string together to form proteins. Within this system there is a built-in fail-safe, in which multiple different codons will result in the same amino acid being used, allowing for natural mutations to occur that won’t affect the end protein that is produced. These synonymous codons have formed the basis of biologists working to create entirely synthetic genomes that still code for fully functioning bacteria, but which can then be altered to our own needs.


“It‘s an important step forward for demonstrating the malleability of the genetic code and how entirely new types of biological functions and properties can be extracted from organisms through genomes that have been recoded,” explains Yale University’s Farren Isaacs to Nature. To achieve the results, the researchers altered the normal genetics of the bacteria to produce synthetic codons that don’t naturally occur in the wild. Using this method, they changed over 60,000 incidences of seven separate codons in the E.coli’s DNA, and found that the genetic function was unaltered. While they are yet to reassemble the DNA and place it into a living cell, the results show great promise that this will be successful.

The same team involved with this latest study has also demonstrated the power that this could infer. They managed to engineer E.coli so that it was turning out amino acids that are not actually present in nature. This impressive feat had the fascinating effect of making the bacteria more resistant to viruses and infection, because the viruses have evolved to exploit the bacteria’s cellular machinery, but could no longer recognize this when the amino acids have been altered and thus can’t infect them. Creating disease-resistant bacteria in such a way could have massive applications.  

Not only that, but engineered bacteria can also be tweaked so that rather than “feeding” off naturally occurring amino acids, they become totally reliant on the synthetic ones produced in the lab. This built-in redundancy would mean that if researchers did create synthetic bacteria and they somehow escaped, they would quickly perish in the outside world as they can’t get the resources to survive.