A machine rapidly modifies bacterial genomes.
Source: “Programming cells by multiplex genome engineering and accelerated evolution”
Harris H. Wang, Farren J. Isaacs, et al.
Nature 460: 894-898
Results: A machine developed by researchers at Harvard, MIT, and Georgia Tech can quickly make thousands of targeted changes to a bacterial genome. Using the machine to modify E. coli bacteria that produce lycopene, an antioxidant found in tomatoes, the researchers took just three days to create a strain that produced five times as much of the chemical as the original.
Why it matters: The machine could dramatically speed the increasingly sophisticated process by which researchers modify microbes to produce biofuels and other useful chemicals. This type of engineering is slow because the scientists typically need to change many interrelated genes, but they can make at most a few changes to the bacterial genome at a time. Automating the process can accomplish in just a few days work that previously would have taken weeks or months.
Methods: Scientists mix bacteria with more than 23,000 different short strands of DNA, each of which could modify one of 24 different genes in a way that could enhance the organisms’ ability to perform a certain task. One altered strand, for example, might make an enzyme more efficient. The new machine subjects vials of the mixture to temperature and chemical cycles that encourage the bacterial cells to take up the foreign DNA, swapping a particular strand into their genomes in place of the native piece it resembles. Within
a vial, the rapidly reproducing bacteria take up more of the foreign DNA in each generation. The researchers examine the simultaneously produced strains and pick the one whose genetic changes make it most efficient at the desired task.
Next steps: Researchers want to improve the efficiency of the device, increasing the proportion of bacterial cells that end up with large numbers of genetic changes. They also plan to extend the technology to human cell lines and to yeast, which is important for making biofuels.