Genetic alteration of woody plant material may allow for more efficient and economical biofuel production, according to research being conducted by separate teams of scientists at Penn State and Mississippi State universities.
Biofuel Efficiency Obstacles
Ethanol subsidies and mandates at the federal and state level are designed to reduce gasoline use and improve the environment. However, diverting corn, sugar, and other food staples to ethanol production has led to concerns about food scarcity, higher fuel prices, and environmental harms ranging from water depletion to an increase in greenhouse gas emissions.
Finding a way to address these concerns is motivating scientists to look for better sources of ethanol production than traditional food staples.
Promising Nonfood Sources
Scientists at Penn State and students at Mississippi State have determined woody plant material is a promising option for ethanol production. This material contains cellulose, which can be converted to sugar for making ethanol.
Converting woody plant material in the stalks of corn, sugar, and other plants to ethanol would not reduce food supplies and would mitigate many of the environmental consequences of diverting existing forestland to crops for ethanol production.
Woody plant material contains large amounts of cellulose, but separating the cellulose from the plant material and converting it to ethanol is currently a difficult and costly process.
The chief biological obstacle to effective production of ethanol from woody pulp material is lignin, a substance that enables plant stalks to bear weight without drooping. The presence of lignin makes it difficult to extract cellulosic material from the plant.
Gene Would Separate Lignin
To overcome this obstacle, John Carlson, professor of molecular genetics, and his colleagues at Penn State are experimenting with modifications to the connections within the lignin. They have inserted a protein gene, taken from beans, between the lignin molecules, enabling easier separation of the valuable cellulose while allowing the lignin to retain its structural rigidity.
Initial results are promising, though more testing is needed, the scientists say.
Enzyme Would Aid Breakdown
Science students at Mississippi State are also attacking the lignin problem through biotechnology. In a project that won a bronze medal at the 2008 International Genetically Engineered Machine competition, the students experimented with naturally occurring enzymes that initiate lignin breakdown.
“The problem with the current way of making ethanol is that resources are limited,” said Caleb Dulaney, one of the two students whose research won the bronze medal, in a December 11 press release. “The plant matter left over after harvesting can provide an almost unlimited resource for biofuel manufacturing.”
“There is no question that recombinant DNA technology—also known as ‘gene-splicing’—could make various plants a more promising source of ethanol production. But there are formidable obstacles, which are more regulatory than technical,” said Henry Miller, a research fellow at Stanford University’s Hoover Institution.
“Although recombinant DNA-modified plants are far more precisely crafted and more predictable than similar plants made with older, ‘conventional’ techniques, they are far more stringently regulated. They undergo repeated case-by-case reviews as field trials are scaled up, and with every minor variation in the genetic construction. A field trial with a recombinant DNA-modified plant is 10 to 20 times more expensive than the same trial with virtually identical plants made with less-precise techniques,” Miller explained.
“The USDA’s and EPA’s approach to regulation, which is decades old, violates the basic principle of ‘proportionality’, which dictates that the degree and intrusiveness of oversight should be proportional to the perceived risk. It explains why relatively few promising plant varieties make it from the laboratory to the field and into commerce,” Miller noted.
E. Jay Donovan ([email protected]) writes from Tampa, Florida.