Researchers Identify Structural Mechanism of Hot Water Pretreatment of Corn Stover for Cellulosic Ethanol Production
26 April 2007
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| A magnified image of a cornstalk particle shows the many tiny pores that pretreatment opens up. Click to enlarge. |
Researchers at Purdue University have discovered that particles from cornstalks undergo structural changes when processed to produce ethanol, an insight they said will help establish a viable method for large-scale production of cellulosic ethanol.
Their research demonstrates that pretreating corn plant tissue with hot water—an accepted practice that increases ethanol yields 3 to 4 times—works by exposing minute pores of the plant’s cell walls, thus increasing surface area for additional reactions that help break down the cell wall. The work is published in the current edition of the journal Biotechnology and Bioengineering.
Plant cell walls are rigid structures made up of a variety of polymers, including cellulose and hemicellulose, which can be converted into sugars that are then made into ethanol. However, cellulose and hemicellulose are held in place by a variety of compounds like lignin, a strong cellular glue that resists treatment and protects cellulose from being broken down.
Using high-resolution imaging and chemical analyses, the researchers determined that pretreatment opens reactive areas within the cells of the corn stover that were previously overlooked. In the next step of processing, these enlarged pores are more easily accessed by enzymes that convert cellulose into glucose for subsequent fermentation into ethanol.
The researchers found that after pretreatment opens corn’s tiny pores, enzymes not only removed more cellulose and hemicellulose from the cell wall, but also removed it at a faster rate.
The smaller 53-75 micrometer corn stover particles are 1.5X more susceptible to hydrolysis than 425-710 micrometer corn stover particles. This difference between the two particle size ranges is eliminated when the stover is pretreated with liquid hot water pretreatment at 190 degrees C for 15 min, at pH between 4.3 and 6.2. This pretreatment causes ultrastructural changes and formation of micron-sized pores that make the cellulose more accessible to hydrolytic enzymes.
The hot liquid water pretreatment process used in the study was originally developed in the Laboratory of Renewable Resources Engineering at Purdue. The study was funded by the US Department of Energy, US Department of Agriculture and Purdue Agriculture.
Resources:
“Microscopic Examination of Changes of Plant Cell Structure in Corn Stover Due to Hot Water Pretreatment and Enzymatic Hydrolysis”; Meijuan Zeng, Nathan S. Mosier, Chia-Ping Huang, Debra M. Sherman, Michael R. Ladisch; Biotechnology and Bioengineering Volume 97, Issue 2 , Pages 265 - 278
Can we supply enough corn stover to do this, without damaging our fragile croplands, by removing this humus-building, soilsaving, water retaing, stover?
Posted by: Mark A | 27 April 2007 at 05:04 AM
Some research shows that you can use about 50% of the corn stover for cellulose ethanol and not harm the land, using no till farming. That would increase the production of ethanol without using corn and without harming the land.
I leave it up to the farmers to decide what they can do and what they can not. Ethanol from cellulose can be a good revenue source for the farmer. I would hope that they would not ruin their land in the process.
Posted by: SJC | 27 April 2007 at 08:01 AM
ALL SCIENTIFIC STUDIES INDICATE THAT CELLULOSE ETHANOL IS VERY GOOD REPLACEMENT FOR PETROLEUM FUELS . IF USED IN ECOLOGICAL MANNER SOIL PRODUCTIVITY CAN BE RETAINED. CEL ETHANOL CAN BRING ABOUT SUSTAINABLE DEVELOPMENT. COUNTRIES LIKE INDIA AND CHINA NEED TO LEAP FROG TO GREEN TECHNOLGIES DIRECTLY. THERE IS NOT ENOUGH PETROLEUM AROUND AND IT IS VERY POLLUTING.
OUR FARMING IS SUFFERING BECAUSE OF UNECONOMIC FARMING AND FARMERS ARE KILLING THEMSELVES DUE TO ECONOMIC FAILURES. CEL ETHANOL CAN BE THE SAVIOUR ON ALL FRONTS.
Posted by: NIRMALSINH WALA | 27 April 2007 at 09:38 PM