Scientists can make a
genome but do not yet
fully understand how
This work showed that scientists can create pieces of DNA over half a million nucleotides long. The researchers didn't create anything newthey basically recreated a known genome. But now that they have done this, there is nothing to stop them from creating a brand new organism from scratch. Nothing but a lack of knowledge about how genomes really work that is.
Scientists can make a big piece of DNA but they really don't understand how a genome works. Which makes creating totally new genomes nearly impossible. But the research done here can help them overcome this problem too.
Scientists can now make new genomes with specific pieces missing and see what effect that has on the bacterium. From this scientists will gain a better understanding of how genomes work by figuring out which bits of DNA an organism needs. And which bits it doesn't.
For example, scientists have been able to get rid of each of the 485 genes normally found in Mycoplasma genitalium
, one at a time. Doing this they established that about 100 of them weren't essential to the bacterium's life. But what happens if they get rid of two at once? Or all 100?
This kind of experiment would be very difficult to do the usual way. But if anything, it would be easier to create a smaller piece of DNA that lacks these 100 genes. Now scientists can really figure out the minimal genome necessary for life. And in the process learn how different genes work with each other to create and run an organism.
Once they get a minimal genome, the next step will be to add back genes that allow the new bacterium to do what the scientists want it to do. For example, let's say they want to make a bacterium that turns plants into hydrogen to be used in fuel cells. The idea is that they would create a genome that can do this, stick it into a bacterium and ship it to the nearest plant processing center.
Of course to do this, scientists need to understand what genes a bacterium needs to make hydrogen. (Scientists have yet to find or create these genes.) And once they find these genes, they need to add them in such a way that the beast can actually do what they want it to do. The end result will be a clean burning fuel made by bacteria.
Why start from scratch?
There are plenty of bacteria to
choose from. Why start from
The old fashioned way of making bacteria that do new things is to mutate or add DNA back to known bacteria that already kind of do the new thing. For example, the idea would be to search for bacteria that can make hydrogen in some way. Then scientists would tweak the bacteria a bit to get them to make hydrogen from the plant source they want.
This process has been pretty successful in other projects. Which begs the question of why start from scratch? Why go through all the trouble of finding and building a minimal genome?
One investigator used a great analogy. Let's say you have a pile of dirt in your backyard and a hole that needs filling. And you have a car and a piece of metal.
One option is to stick the metal onto the car and push the dirt to fill in the hole. The other option is to go into the garage and create a bulldozer from scratch. Why would you go into the garage and do all that work when the tools are already there?
The same question can be asked with designer bacteria. Why create a genome from scratch when there are already plenty of genomes out there that, with some tweaking, can be trained to do what you want them to do?
One possible advantage is versatility. Once a minimal genome is created, it should be relatively simple to add genes and test in the new bacteria. This might definitely speed up the process of mutating/creating bacteria from what is currently lying around.
In our garage analogy, the idea would be that the owner sets up an automatic assembly line that can quickly create new motorized vehicles. The owner would set it up so it is easy to add pieces to create a bulldozer, tractor, or whatever else he or she needs for the yard work to get done. After the initial time lag, new machines could quickly come off the assembly line.