BETTER THAN BLEACH
Enzyme Could Improve Paper Industry, Ethanol Production

Working in a lab filled with beakers and bubbling bioreactors, bioengineering professor Christine Kelly is addressing two areas of global concern: reducing the use of harmful pollutants and making clean energy production more economical.

Kelly and her students are developing methods to mass produce an enzyme secreted by white-rot fungi that could reduce the use of toxic chlorine in paper manufacturing and improve ethanol production.

The enzyme, manganese peroxidase, breaks down lignin, a substance that protects cellulose in trees and plants from microbial attack. To make paper, the lignin must be removed and the pulp bleached. The nontoxic enzyme could be used instead of chlorine.

When converting biomass to ethanol, lignin must also be removed. Using the enzyme to aid lignin removal could lower the high temperatures and eliminate some of the chemicals currently used in the pre-treatment process, reducing the cost of ethanol production.

All of this sounds wonderful, but the problem is that manganese peroxidase is produced naturally in only very small amounts. “This enzyme has not been used commercially because not much of it is secreted by the fungi,” Kelly says. “And it’s difficult to make in alternative hosts.”

But Kelly used genetic engineering to transfer a gene from the white-rot fungi into a yeast that can be cultivated in a bioreactor. If large volumes of the enzyme can be produced, it could become a commercially viable product.

With help from three PhD candidates, three undergraduate students, and a $210,000 grant from the National Science Foundation, Kelly has increased the concentration of the enzyme cultivated more than 1,000 times since beginning the project.

“We’ve made about as much progress as possible on the cultivation side,” says Kelly, who is part of the Biological and Environmental Systems Research Cluster. “But there are more improvements to be made with genetic engineering.”

Kelly received a $200,000 Sun Grant to study how the enzyme could improve ethanol production. Teaming up with Mike Penner in OSU’s Department of Food Science and Technology, and her husband Curtis Lajoie, a research professor in the School of Chemical, Biological, and Environmental Engineering, Kelly hopes her research will lead to a new product for the ethanol industry.

“Now that cellulosic ethanol is becoming more of a commercial enterprise, lignin-degrading enzymes are going to reach the market place eventually,” Kelly says. “Manganese peroxidase is from a class of under exploited enzymes. Other classes of enzymes are already commercially available, and I think this one will get there, too.”

With continued research support, Kelly and her students are well on their way to making the world a greener place.

Photo: Bioengineering professor Christine Kelly (right) and undergraduate researcher Chris Barnhart inspect a solution containing the enzyme manganese peroxidase in Gleeson Hall.