Creating Ethanol with Bug Guts
By Bill Baum
 A crescendo of events has caused society and the body politic to demand a homegrown, sustainable, renewable energy source to break our dependence on foreign oil. Oil prices are skyrocketing as worldwide demand for fossil fuels has reached all-time highs. Our national security is threatened as much of the U.S. fuel supply comes from politically unstable parts of the world.
One solution to our energy needs is the economic production of biofuels, such as ethanol from agricultural resources. The key to cost-effective production of biofuels lies in the discovery of novel enzymes to convert agricultural biomass to clean-burning fuel. One rich source of these enzymes has been found in the hind guts of termites.
Historically, Brazil has been very effective in producing ethanol from the juice of sugar cane, while the U.S. has relied on converting the starch found in corn kernels into fuel ethanol. But with success comes some complications.
In the U.S. only a finite amount of corn can be used without creating imbalances with other major industries, such as animal feed, which is currently the largest consumer of corn. It is estimated that in 2006, the U.S. will produce over five billion gallons of ethanol from corn and that the upper limit will be about 15 billion gallons, which will represent less than 10% of total transportation fuels at that time. Corn as a feedstock just isn’t enough for our fuel needs.
Biomass –which can include any number of abundant agriculture resources, such as agricultural waste (i.e. corn stover, sugar cane bagasse) or dedicated energy crops (i.e. switchgrass) – needs to be developed as a renewable feedstock for ethanol. Oak Ridge National Laboratory recently published a report called the Billion Ton Annual Supply, which mapped out a range of crops that could easily provide the biomass necessary to produce at least 100 billion gallons of ethanol on an annual basis.
Although biomass is readily available, the technology that works so well for cane juice and starch just isn’t viable for the creation of biomass-based ethanol. More robust enzymatic processes are required to convert the cellulose found in plants into ethanol.
To find out how to make this conversion work, Diversa took a look at nature to see how she converted biomass into energy. At the top of the list was the ubiquitous termite who can convert 95% of what it consumes into energy within 24 hours. We discovered it’s not the termites themselves that are doing this remarkable transformation, but rather the bacteria and protozoa that inhabit their guts. These microbes generate a broad range of enzymes that degrade the cellulosic materials into fermentable sugars.
With the goal of mimicking nature, Diversa is creating a “cocktail” of high performance enzymes from the termite gut for use as industrial ethanol production enablers. For each experiment, we have to dissect and pool about 2000 individual termite intestines. Using proprietary DNA extraction and cloning technologies, we have been able to isolate the cellulose degrading enzymes. While we are in the early stages of this work, we have found the initial results very promising.
So the race is on to develop biomass as a sustainable, renewable fuel source. Cellulosic ethanol has enormous potential for fueling our future, and many prominent public and private companies are working to make this fuel source a near-term reality at the pumps. Who would have thought that the answer to our long-term renewal fuel needs might lie in the guts of the common termite?
Since 1994, Diversa has been searching the globe for unique biodiverse organisms that will yield novel enzymes that can be applied to all types of industrial processes to improve performance and reduce costs.
Bill Baum is executive vice president of Bioscience products at Diversa Corporation.
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