Single Microbe Yields Ethanol, Plus Eco-Friendly Glue

Squeezing more ethanol from cellulose—the basic material from which all plants are made—is still a lofty goal for scientists. The process uses expensive enzymes that are limited in their ability to convert stubbornly rigid plant cells walls into fuels.

Now, an Agricultural Research Service (ARS) microbiologist has discovered a way to boost cellulosic ethanol production, with the help of some unusually hardy bacteria.

Paul Weimer, who works at the agency's U.S. Dairy Forage Research Center in Madison, Wis., is tapping the plant-degrading powers of Clostridium thermocellum. Thanks to this heat-loving microbe, which thrives in 145-degree-Fahrenheit environments and doesn't require oxygen, he's been able to create not only ethanol, but an all-natural wood glue as well.

According to Weimer, this bioadhesive could be a marketable byproduct of cellulosic ethanol production. It represents an added value and a means of potentially offsetting the high costs that currently inhibit the commercial production of cellulose-based fuel in the United States.

Even better is that Weimer's method relies on a potentially cheaper, more streamlined ethanol-making process called consolidated bioprocessing. Instead of using two reactors, enzymes, plus yeast—as standard cellulosic ethanol production requires—this approach uses only one reactor and a single industrious microbe that makes its own enzymes.

The idea for a bioadhesive came to Weimer while observing Clostridium bacteria under a microscope breaking down bits of alfalfa. He saw that during the conversion of plant fiber ethanol, the bacteria latched onto the fiber with such fierceness that the only way to break the bond was to destroy the microbes and their sticky adhesive.

With scientists at the USDA Forest Service's Forest Products Laboratory in Madison, Weimer has found that this bioadhesive is tough enough to replace up to 70 percent of the petroleum-based phenol-formaldehyde that's used to manufacture plywood and other pressed-wood products.

Read more about this research in the April issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.