New Yeast Strain is Step Closer to Cellulosic Ethanol

Breakthrough yeast strain offers a move forward for efforts to make biofuels from a greater variety of non-food crops.

The promise of biofuels is genuine and sincere. Rather than taking carbon that's been fossilized for untold millions of years and sending it into our atmosphere the second we burn it, the manufacture and use of biofuels takes us much closer to greenhouse gas neutrality.

Sure, the combustion of biofuels does produce carbon dioxide, but the plants from which the fuels are made remove carbon dioxide directly from the atmosphere as they grow. Additionally, ethanol just so happens to burn cleaner as compared to petroleum based hydrocarbons.

Still, I know that I'm hardly alone in finding it more than a little perverse to divert perfectly good crops away from the food supply toward the manufacturing of ethanol. Corn and sugar cane are currently prized for the making of ethanol, as their sugars are easily accessible for conversion to fuel. Our best long term hopes are in the realm of cellulosic ethanol, made from more fibrous plant matter such as the stalks of the corn as well as such woodier, non-food plants as switchgrass. Switchgrass is particularly appealing due to it being a relatively low-effort crop which grows easily in a range of conditions, as well as to its high potential energy value.

So far, the challenges to cellulosic ethanol really taking off hinge on the effort (and by extension, the cost) required to get at the sugars that they contain. The additional effort required to make ethanol from fibrous plant material as compared to making it from corn pretty much doubles the cost. It's a stated goal of the federal government to make cellulosic ethanol much more cost-competitive, and ongoing research and development breakthroughs continue to bring these production costs down. And a just-announced finding by researchers at Indiana's Purdue University will no doubt help things along this path.

As PhysOrg has reported, an agricultural and bioengineering research team at Purdue has successfully genetically engineered a strain of yeast that is capable of converting the sugars contained in woodier plant materials such as corn stalks and switchgrass. An added and beneficial characteristic of the new strain of yeast is its resistance to acetic acid. Acetic acid is a common component of plant life and is given off along with the sugars, but it can hinder the fermentation activity that the yeast provides, slowing the conversion process and ultimately decreasing the yield of ethanol.

The Purdue team's research, currently published in the journal Applied Microbiology and Biotechnology, is supported by funding from the US Department of Energy and will reportedly pursue even more improvements to the yeast's efficiency and resistance to chemical agents that slow the sugar-to-ethanol conversion process.

source: tonic