Wednesday, October 24, 2012

GE for sustainability.

Late last week there we had the reports of engineered algae possibly being used to produce the ethylene for plastic - something that would reduce our dependence on fossil fuel sources. Well here's another use of genetic engineering that could help us with that.

Vast swathes of corn are grown in the US for use in the production of biofuel. One of the problems with this is that parts of the plant that we currently use for producing fuel is the bit with easily accessible sugars for the yeasts that produce the food. This is otherwise known as the edible bit. The rest of the plant, the stalks, the foliage are wasted. The stalks and foliage of the plants contain to much cellulose, a component of the cell walls, made of sugar, that is incredibly hard to break down. As a result there's a lot of arable land being used for fuel production that could otherwise be being used for food production - something we're going to need a lot more of in the coming decades.

A group in Massachusetts has engineered corn so that the enzyme to break down the cellulose is already inside the cell where it can get easy access to the cellulose. On the face of it, it's a silly thing to do, if you have an enzyme in the plant cells that break down cell walls, there will be enzymes inside the cells, crippling the plant as it tries to grow. Which is where they get clever. When the plant is growing, the enzyme is produced in an inactive state. They've inserted a protein sequence called an intein that that excises itself out of a larger protein, specifically one that only works at high temperatures. The plant grows normally, you harvest the edible bits for food and ship the rest off to the fuel processing plant where it is heated, the intein activates, cut's itself out of the enzyme which then goes to work on the cellulose in the cell walls, breaking it down and freeing up all the sugar for the yeasts.

And you get the same benefit that you get with the ethylene producing bacteria, you're not introducing any new carbon into the atmosphere. It's not production ready and even when it is there a number of other factors to consider when trying to make farming more sustainable, but it's an ideal example of how GE technology can help.

Unless of course you consider GE is to be inherently evil.

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