Bioengineered corn can digest itself in the name of biofuels

Ars Technica » Scientific Method 2012-10-23

The plant left behind after corn is harvested could be a source of both biofuels and the enzymes that create them.

So far, the first generation of biofuels is being made from things like corn, palm oil, and sugar cane. But only a small part of these plants—a part we'd already been using for other things—is actually made into fuel. Being able to make biofuels from the rest of the plant would allow us to get more from existing crops, use the leftover biomass from food production, and allow us to process plants that grow on marginal terrain.

Unfortunately, most of the carbon in a plant is locked up in cellulose, a very tough polymer made from simple sugar molecules. Before we turn a plant into biofuel, we need to figure out how to break down the cellulose. Right now, that process takes harsh conditions and long treatments with enzymes, which significantly adds to the cost. But some bioengineers at a company in Massachusetts have made a plant that carries an enzyme that can help digest itself—but the enzyme remains inactive until the plant is processed.

Hemicellulose is a major component of plant cell walls. Its presence helps protect cellulose from digestion, so digesting it not only liberates sugar for making biofuels, but it also makes the sugar in cellulose easier to access. Digesting away hemicellulose is thus a key early step in biofuel production, and requires either harsh chemicals or expensive enzyme treatments.

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