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Thursday, June 21, 2007

Biofuels: Beyond Corn

Gene sequencing could help make more energy-efficient biofuels practical.

By Emily Singer

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Functional fungi: Sequencing the genome of the common button mushroom, Agaricus bisporus, could help scientists identify enzymes that can efficiently break down plants into simple sugars, which can then be fermented into ethanol.
Credit: Darkone, Wikipedia

In an attempt to find cheaper and more efficient routes to biofuels, researchers are turning to genomics. Scientists at the Department of Energy (DOE) have just selected the button mushroom as one of their latest picks for DNA sequencing, hoping to co-opt fungi's plant-degrading power to produce ethanol more cheaply. Efforts are also planned to sequence the genomes of the eucalyptus tree and foxtail millet, a grass closely related to switchgrass.

Most ethanol in the United States is derived from corn kernels, hence it consumes a valuable food and agricultural product. What's more, growing corn is itself an energy-intensive process. Grasses, agricultural waste such as cornstalks, and even trees could potentially provide a better feedstock: they produce much more biomass per acre than corn with less energy expenditure. However, these plant sources of ethanol require extensive preprocessing to release sugars from the cellulose in them, making the procedure too expensive to compete with traditional gasoline or corn-based ethanol.

With current methods to make cellulosic ethanol, the plant matter is broken down with chemicals and a costly mixture of synthetic enzymes. In an attempt to find a cheaper method, the DOE's Joint Genome Institute (JGI), based in Walnut Creek, CA, is sequencing the genomes of approximately 20 "biomass degraders," such as the button mushroom, which feed off decaying plants by degrading the cell walls and then using the resulting sugars for energy. "By sequencing organisms involved in natural biomass breakdown, you can hopefully identify superior enzymes and reactions that could be incorporated into fermentation organisms to improve the process," says Jonathan Mielenz, director of the Bioconversion Laboratory at Oak Ridge National Laboratory, in Oak Ridge, TN.

Scientists are also sequencing the genomes of various crops to spur efforts to engineer faster-growing and hardier plants for biofuel production. "The key to making [cellulosic ethanol] workable is getting the most biomass you can per acre of land," says Jim Bristow, head of the community sequencing program at the JGI. "Understanding the traits that lead to rapid growth or growth in particular climates will be important as we improve all these biomass feedstocks."

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Comments

  • Other Uses
    rajnz on 06/21/2007 at 2:01 AM
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    I wonder if the knowledge gained from the functions of plant-degrading genes can be put to other therapeutic uses in humans. I am thinking of the build-up of cellular rubbish in our cells which is one of the principal causes of ageing. Maybe this could be used to design chemicals or molecules to help us get rid of this rubbish
    Rate this comment: 12345
  • Eating ourselves out of house and home
    oconnmic on 06/21/2007 at 10:13 AM
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    This is a new twist on the old saw! 

    Does anyone really think it's wise to consume your food supply to fuel your car and air condition your home?  Especially since it takes about the same amount of fossil fuel to create the biofuel as it does to make the gasoline, at least for now.  And coal and other carbon based sources of energy are abundant on the planet as is nuclear fuel.  Clean it up, yes, but don't make food supplies your source of power.  That's just crazy and intuitively obvious. We can live without cars and air conditioning but not food.
    Rate this comment: 12345
    • Re: Eating ourselves out of house and home
      phoffman on 06/21/2007 at 1:08 PM
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      You assume that the worlds or more specifically the U.S's agricultural resources are limited. As is any other business, expansion of crop production is limited only by demand. Most cropland in the U.S. is used to raise animal feed particularly corn.If you think there is a shortage of acreage in the U.S. you are wrong. the government currently pays farmers not to plant many crops to support price floors. 
      Continue to sit & freeze in the dark, instead of lighting a candle.
       
      Rate this comment: 12345
      • Re: Eating ourselves out of house and home
        theblight on 06/24/2007 at 6:58 PM
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        As usual, the numbers are what counts.  well less than 10% of US cropland is in set aside, (conservation reserve) so don't imagine that biofuel demand couldn't easily reach levels that would set food against fuel.  It is true that we use a substantial portion of our grain crops to feed animals, and that if we moved toward more vegetarian  diets that would relieve some of the competition, but also remember that we are looking to crops to produce the raw material for home heating, future plastics, to replace wide use of synthetic (petroleum based) fiber in clothing, even plant based medicines

        theblight
        Rate this comment: 12345
  • Parasitic Plants
    mkogrady on 06/21/2007 at 2:04 PM
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    It seems to me that IF we're looking for a source of genetic materials for the enzymes needed to convert complex starchy materials into simple digested sugars for fermentation may be found in some more exotic parasitic plants found throughout the world. These plants rely on a host plant of course, unlike decaying plant material like Mushrooms and fungi.

    UCLA has some decent info: See link
    http://www.botgard.ucla.edu/html/botanytextbooks/lifeforms/parasiticplants/index.html
    Rate this comment: 12345
  • Algae much higher efficiency
    nekote on 06/22/2007 at 11:39 PM
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    Studying the genetics of algae that can "store" sunlight as lipids would seem to be ever so much more valuable, as compared to familiar agricultural crops.

    Alternatively, a method to store sunlight in some mode of electricity.

    It would seem simpler and very much more likely to be of greater value to work on certain simple algae.  As opposed to expending much time, money and effort on very much more complicated, if familiar, "crops" that are comparatively much less efficient at storing solar energy.
    Rate this comment: 12345
  • Economics of getting alternative energy
    barryleon on 07/04/2007 at 1:15 PM
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    It seems obvious that using agricultural waste will be more economically viable than competing with food production.  However, all alternative solutions need to compete with existing oil and there are two hurdles involved.  One is competing at the current price of oil (this is not a problem for many new technologies with oil surpassing $50 a barrel), and the other is getting industry to lay out large capital expenditures when faced with the possibility that, as unlikely as it may seem to us today, oil could fall to below $40 a barrel sometime in the future.
    One answer is the permanent imposition of a “conditional” tax on oil based fuel.  With the cost of oil over a particular threshold (maybe $40 a barrel) there would be no tax imposed.  However, if the price fell under the threshold, a tax on the fuel at the pump would go into effect and would make it equivalent to the base price.  Industry could then safely invest the billions of dollars necessary to develop bio-fuels, tar sands, coal gasoline or any other rational possibility that works over a certain price.
    It wouldn’t hurt either if Congress would give such energy independence providing ideas, some extra tax relief.
    Rate this comment: 12345
  • Feedstock
    mlmccarty on 07/09/2007 at 10:00 PM
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    So why not choose Kudzu....Anyone who has been in the south knows this plant grows very rapidly.
    Rate this comment: 12345
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