U.S. researchers say they've modified a bacterium to create an important component of a high-energy biofuel that could eventually augment limited supplies of fuels such as JP-10 in rockets and other aerospace uses.

Scientists at the Georgia Institute of Technology and the U.S. Department of Energy's Joint BioEnergy Institute in California say they've successfully modified a bacterium by inserting tree enzymes to synthesize pinene, a hydrocarbon that could potentially replace high-energy fuels.

In a study published in the journal ACS Synthetic Biology, the researchers report increasing the production of pinene to six times that of earlier bioengineering attempts.

"We have made a sustainable precursor to a tactical fuel with a high energy density," Georgia Tech chemistry Professor Pamela Peralta-Yahya says. "We are concentrating on making a 'drop-in' fuel that looks just like what is being produced from petroleum and can fit into existing distribution systems."

High-energy density fuels such as JP-10 are important in aerospace in applications where minimizing fuel weight is important, the researchers said, but the amount of such fuels that can be obtained from a barrel of petroleum is limited and pushes the price to about $25 a gallon.

Most research on alternative fuels has concentrated on bio-diesel and ethanol while in comparison little work has focused on high-energy fuel replacements.

Peralta-Yahya and her colleagues worked to better previous efforts by using enzymes introduced into E. coli bacterium.

Researchers managed to increase the output of pinene to 32 milligrams from each liter, an improvement over earlier efforts, but a higher figure is needed to compete with petroleum-based fuels.

A 26-fold increase in pinene production will be needed to be competitive, but Peralta-Yahya says she believes that can eventually be attained with the bioengineered E. coli.

"Even though we are still in the milligrams per liter level, because the product we are trying to make is so much more expensive than diesel or gasoline means that we are relatively closer," Yahya says.

"If you are trying to make an alternative to gasoline, you are competing against $3 per gallon," Yahya added. "That requires a long optimization process. Our process will be competitive with $25 per gallon in a much shorter time."

In addition to supplementing limited and expensive supplies of petroleum-based JP-10, the high-energy biofuel could lead to development of a new generation of more powerful engines, the researchers said.