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Special
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Written by Sabrina Deparine
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Tuesday, 15 June 2010 10:02 |
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Page views: 816 |
A team of three scientists from the Purdue University worked on modifying a strain of yeast that can help improve the cellulosic biofuel production.
The team consists of Nancy Ho, research professor for Chemical Engineering; Nathan Mosier, associate professor for Agricultural and Biological Engineering; and Miroslav Sedlak, research assistant professor for Agricultural and Biological Engineering. They were able to discover what they called as “Ho yeast strain” after Nancy Ho who was the first one to work on the project.
Based on their experiments, the Ho yeast strain can ferment all five types of sugar used in biofuel production namely arabinose, xylose, galactose, manose and glucose. She and her team utilized genes extracted from fungus in order to re-engineer a new type of yeast strain that can contribute to an increase in the amount of ethanol produced from cellulosic plant materials.
 Most plant materials contain an average of 10% arabinose. Technically, the process devised and employed by the team in breaking down plant sugars is the same as those currently used in the industry. However, the addition of fungal genes allows the Ho yeast strain to create the necessary enzymes that include arabinose in its chain.
Aside from the arabinose-fermenting yeast, Ho, Mosier and Sedlak were also able to develop yeast strains that are more resistant towards acetic acid. Acetic acid, the main ingredient in vinegar, is released along with sugars prior to the fermentation process in ethanol production.
However, one downside of using the Ho yeast strain is the acetic acid gets into the yeast cells which, in turn, slow down the fermentation process. This can actually make ethanol production more expensive. As such, this new discovery is not yet viable and recommended for industrial and commercial-scale processes.
To address this issue, Ho and her team have studied the genes from more resistant strains to determine which ones can make the Ho yeast strain more resistant to acetic acid. By far, they are only able to improve the expressions of the identified genes to increase the yeast’s resistance to acetic acid.
The team will continue to work on this project in order to improve the new yeast strain, making it more helpful to industrial ethanol production as well as making it more resistant to various inhibitors.
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